Hong Kong’s leader says an estimated 100 protesters remain holed up in one of the city’s main universities that had been blockaded by police.

Leader Carrie Lam said Tuesday that 600 protesters had left the Hong Kong Polytechnic campus, including 200 who are under 18 years old.

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Hong Kong youths leave from the Hong Kong Polytechnic University to surrender to police in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Hong Kong’s leader says an estimated 100 protesters remain holed up in one of the city’s main universities that had been blockaded by police.

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Slogans are written on the glass walls in Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Slogans are written on the glass walls in Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester takes the last look from one of the frontline barricades before leaving to surrender to police at the the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester takes the last look from one of the frontline barricades before leaving to surrender to police at the the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A barricaded bridge and the words "Restore Hong Kong" are seen near the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A barricaded bridge and the words "Restore Hong Kong" are seen near the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A statue of Goddess of Democracy and five black balls to represent the five demands are set up by protesters looking over the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A statue of Goddess of Democracy and five black balls to represent the five demands are set up by protesters looking over the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester sleeps in the open near graffiti which reads "How much will you lose, before you wake up" in the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester sleeps in the open near graffiti which reads "How much will you lose, before you wake up" in the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police have surrounded the university and are arresting anyone who leaves. Lam said those under 18 would not be immediately arrested but could face charges later.

Hong Kong youths leave from the Hong Kong Polytechnic University to surrender to police in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Hong Kong youths leave from the Hong Kong Polytechnic University to surrender to police in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Slogans are written on the glass walls in Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Slogans are written on the glass walls in Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester takes the last look from one of the frontline barricades before leaving to surrender to police at the the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester takes the last look from one of the frontline barricades before leaving to surrender to police at the the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A self made catapult is left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Molotov cocktails, gas canisters and other improvised weapons are left over at the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A barricaded bridge and the words "Restore Hong Kong" are seen near the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A barricaded bridge and the words "Restore Hong Kong" are seen near the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

Police cordons off the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A statue of Goddess of Democracy and five black balls to represent the five demands are set up by protesters looking over the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A statue of Goddess of Democracy and five black balls to represent the five demands are set up by protesters looking over the Hong Kong Polytechnic University campus in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester sleeps in the open near graffiti which reads "How much will you lose, before you wake up" in the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)

A protester sleeps in the open near graffiti which reads "How much will you lose, before you wake up" in the Hong Kong Polytechnic University in Hong Kong on Tuesday, Nov. 19, 2019. Police tightened their siege of the university campus where hundreds of protesters remained trapped overnight Tuesday in the latest dramatic episode in months of protests against growing Chinese control over the semi-autonomous city. (AP PhotoNg Han Guan)