(The Center Square) – Local and federal authorities are investigating what FBI Director Kash Patel said was a "targeted terror attack" in Boulder, Colo., Sunday in which multiple people were set on fire during an event hosted by a group that seeks the release of Israeli hostages held by the anti-Israel terrorist group Hamas.

The suspect in the attacks was arrested at the scene, authorities said, but was not immediately identified.

"The initial callers indicated that there was a man with a weapon and that people were being set on fire," Boulder Police Chief Steve Redfearn said during a Sunday afternnoon news conference, adding that there were multiple victims but he couldn't say exactly how many.

Redfearn said the attack occurred during a pro-Israel demonstration on Pearl Street near the county courthouse but authorities were still investigating if it was antisemitic in nature.

Colorado Gov. Jared Polis called the attack a "heinous act of terror" in a post on X.

"I am closely monitoring the situation in Boulder, and my thoughts go out to the people who have been injured and impacted by this heinous act of terror," Polis wrote. "Hate-filled acts of any kind are unacceptable. While details emerge, the state works with local and federal law enforcement to support this investigation."

This is a developing story.