BELÉM, Brazil — Activist groups and United Nations security clashed in chaotic scenes late Tuesday after protesters appeared to force their way into the COP30 climate conference venue, in the most serious act of unrest seen in years inside one of the annual gatherings.

Security personnel were barricading the entrance with tables around 7:30 p.m. local time (5:30 p.m. EST) after forcing out demonstrators who waved yellow flags protesting oil drilling in the Amazon.

At least one security guard appeared injured.

A spokesperson for the U.N. climate body on the scene said they were unable to comment.

“It was people running, trying to storm inside,” said Enric Noguera Marcet, with the organization Plant Based Treaty, who was nearby when the protest erupted. “They [U.N. security] forced them out. Security were very aggressive. They grabbed some people by the neck, pushed people to the ground. I saw some punches as well.”

Footage shared with POLITICO shows also security forces manhandling some of the protesters. Parts of the venue, in the capital of the northern Brazilian state of Pará, were evacuated.

In the video, a large group of protesters stood shouting and chanting holding banners and a large Palestinian flag. Some of them were wearing traditional Indigenous clothing and headgear. In one heated moment, protesters could be seen standing up to guards and guards shoving them backward.

In another video shared with POLITICO that could not be immediately verified, the protesters could be seen storming into the hall of the talks from outside with guards running to try and encircle them.

The COP site is temporarily a U.N. diplomatic zone, and security is managed by the U.N.’s own security team, not the Brazilian government