Climate activist Greta Thunberg and several others were arrested Wednesday after occupying a University of Copenhagen building to call for an academic boycott of Israeli universities, AFP reports according to Danish media.

Images on the daily Ekstra Bladet website showed the 21-year-old activist, wearing a black-and-white keffiyeh shawl draped over her shoulders, being escorted out of a campus building by police.

Thunberg herself shared images on Instagram of riot police entering a building where the group “Students against the Occupation” was staging a protest.

“I can’t confirm the names of those arrested, but six people have been arrested in connection with the demonstration,” a Copenhagen police spokesman told AFP. Three of them “are suspected of forcing their way into the building and blocking the entrance”, he said.

The six were released several hours later, the spokesman told AFP, and video footage published by Ekstra Bladet showed Thunberg walking out of the police station.