A man reportedly set people on fire in Boulder, Colorado, leaving multiple individuals injured, the city’s police chief said, as people gathered for a “peaceful” pro-Israeli demonstration.

A suspect is in custody and police are investigating what FBI officials immediately called “a targeted terror attack” – though the local authorities said it was too early to define the attack.

“When we arrived, we encountered multiple victims … with injuries consistent with burns,” Boulder Police Chief Stephen Redfearn said Sunday.

Redfearn told reporters that it was too early to discuss a motive but that witnesses were being interviewed.

“It would be irresponsible for me to speculate on motive this early on,” he said.

The man threw bottles that apparently contained flammable liquid that hit the ground and exploded in flames, multiple law enforcement officials briefed on the investigation told CNN, noting the exact number of bottles was unclear.

At least two individuals have been taken to the hospital, according to those officials.

“We are aware of and fully investigating a targeted terror attack in Boulder, Colorado. Our agents and local law enforcement are on the scene already, and we will share updates as more information becomes available,” FBI director Kash Patel said in a social media post Sunday.

FBI personnel are at the scene along with local law enforcement, according to FBI Deputy Director Dan Bongino.

“We are investigating this incident as an act of terror, and targeted violence,” Bongino posted to social media.

“All of the necessary assets will be dedicated to this investigation.”

While the suspect has not been identified by police, federal charges are expected in the case, a source familiar with the investigation tells CNN.

FBI agents and federal prosecutors are currently reviewing the circumstances of the incident to determine whether the individual will be charged with terrorism or under other possible federal criminal statutes, the source said.

The source stressed potential mental health concerns have not yet been ruled out, which could factor into any charging decision.

Boulder Police said they were evacuating several blocks of the typically popular pedestrian mall area, saying that there were “several victims” in the attack without providing further details.

The reported attack took place at the Boulder Run for Their Lives event, the Anti-Defamation League said on social media.

The weekly gathering of Jewish community members is meant to support the hostages taken during the October 7 attacks in Israel in 2023.

The incident happened ahead of the holiday of Shavuot, according to the ADL – a Jewish holiday which celebrates the giving of the Torah to the Jewish people on Mount Sinai.

“We are saddened and heartbroken to learn that an incendiary device was thrown at walkers at the Run for Their Lives walk on Pearl Street as they were raising awareness for the hostages still held in Gaza,” Boulder’s Jewish community said in a joint statement to CNN.

Colorado Governor Jared Polis said in a statement that he was “closely monitoring” the situation, adding that “hate-filled acts of any kind are unacceptable.”