California authorities say they have not ruled out the possibility of a hate crime.

Paul Kessler, 69, died on Monday after falling and striking his head after a confrontation during duelling demonstrations in Thousand Oaks, northwest of Los Angeles, authorities said.

Ventura County Sheriff’s Department said authorities had not ruled out the possibility that a hate crime had taken place.

“Witness accounts indicated that Kessler was involved in a physical altercation with counter-protestor(s),” the sheriff’s office said. “During the altercation, Kessler fell backwards and struck his head on the ground.”

The sheriff’s office said that it had not taken any suspect into custody following the incident, which appeared “to be isolated and not part of a large effort”.

Footage on social media appeared to show Kessler lying on the ground bleeding and holding his head.

The Jewish Federation of Greater Los Angeles said in a statement on social media that Kessler had been struck in the head by a megaphone wielded by a pro-Palestinian protester and it would not tolerate “violence against our community”. The group did not provide a source for its claim.

Michael Barclay, a local rabbi, urged the public against jumping to conclusions about the incident.

“I just got off the phone with the Chief of Police,” Barclay said on X, formerly Twitter.

“They have conflicting reports of what happened, and they did interview the suspect that is identified in social media at the event. They have no video.”

The incident comes a month after Hamas launched a surprise attack on Israel that Israeli officials say killed more than 1,400 people, mostly civilians.

Israel’s bombardment of Gaza in response has killed more than 10,000 people, according to the Ministry of Health in the Hamas-governed enclave.