Hong Kong police using tear gas and batons fought running battles Monday with protesters who tried to break through a security cordon that trapped hundreds of them at the city’s Polytechnic University.

Protesters advanced on the police from outside the cordon, while others emerged from the campus, their trademark umbrellas at the fore. Police used tear gas and, in some places, swooped in to subdue protesters and make arrests.

For days, protesters fortified the campus to keep police from getting in. Cornered by authorities, they were trying to get out.

Protesters stand on the steps of the Hong Kong Polytechnic University in Hong Kong, Monday, Nov. 18, 2019. Hong Kong police have swooped in with tear gas and batons as protesters who have taken over the university campus make an apparent last-ditch effort to escape arrest. (AP PhotoAchmad Ibrahim)

Protesters stand on the steps of the Hong Kong Polytechnic University in Hong Kong, Monday, Nov. 18, 2019. Hong Kong police have swooped in with tear gas and batons as protesters who have taken over the university campus make an apparent last-ditch effort to escape arrest. (AP PhotoAchmad Ibrahim)

Police used water cannons, tear gas and rubber bullets, while protesters used Molotov cocktails, arrows and bricks

It wasn’t clear if any of those inside escaped.

Police had stormed the campus overnight and made dozens of arrests before retreating. They are intent on talking all the protesters into detention.

The battles are part of six months of anti-government protests that have rocked the semiautonomous Chinese city.