Los Angeles police today arrested a man alleged to have stabbed another man in the chest with a knife or sharp object during an altercation that broke out at dueling vaccine protests in front of Los Angeles City Hall on Aug. 14, the department announced via Twitter.

Eric Cohen, 30, of Long Beach has been booked on suspicion of attempted murder and is being held at the Metropolitan Detention Center in Los Angeles on a $1 million bail, according to police.

Police said several search warrants have been filed in Los Angeles and Orange counties in connection to the case. Detectives believe there was a second violent attack that took place during the same fight, however, no victims or witnesses have come forward, the department said.

Vaccine supporters had gathered for a “No Safe Space For Fascists”rally at the intersection of First and Spring streets, followed one hour later by a “Choose Freedom March” against “medical tyranny.”

At the peak of the rallies, about 500 anti-vaccination protesters were on City Hall’s South Lawn and about 30 to 50 counter protesters were at First and Spring streets, according to police. The LAPD deployed 100 personnel to the event.

City News Service contributed to this story.