Thousands of mainly young people joined Swedish teen activist Greta Thunberg for a peaceful climate march Friday through the city of Bristol, in southwest England.

Ahead of the march, local police had expressed concern that the popularity of the event could lead to risks to protesters.

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Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Thousands of mainly young people joined Swedish teen activist Greta Thunberg for a peaceful climate march Friday through the city of Bristol, in southwest England.

Climate activist Greta Thunberg, from Sweden, center, stands with other protestors as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

The police were criticized for their warning in the run-up to the event. Protest organizers, Bristol Youth Strike 4 Climate, said in a tweet that they had "no time for being patronised.” They had arranged for festival barriers, more than 80 stewards and a safe zone for young children.

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, fourth left behind banner, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, fourth left behind banner, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

In the event, the march, which Avon and Somerset Police said attracted more than 15,000 people but which Thunberg said involved “at least 30,000” braving the pouring rain, passed off without incident.

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

The police were criticized for their warning in the run-up to the event. Protest organizers, Bristol Youth Strike 4 Climate, said in a tweet that they had "no time for being patronised.” They had arranged for festival barriers, more than 80 stewards and a safe zone for young children.

In a speech, the 17-year-old Thunberg said “nothing is being done to halt this crisis despite all the beautiful words and promises by our elected officials.”

Follow AP’s climate coverage at https://apnews.com/Climate

Climate activist Greta Thunberg, from Sweden, center, stands with other protestors as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center, stands with other protestors as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, fourth left behind banner, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, fourth left behind banner, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)

Climate activist Greta Thunberg, from Sweden, center left, marches with other demonstrators as she participates in a school strike climate protest in Bristol, south west England, Friday, Feb. 28, 2020. (AP PhotoMatt Dunham)