San Francisco police arrested a suspect they believe is responsible for the unprovoked attack that involved three Asian victims, authorities said on Wednesday.

Officials booked 43-year-old Michael Lopez at San Francisco County Jail while investigations are ongoing regarding a case of assault with a deadly weapon, assault and battery, a hate crime enhancement, and possession of suspected methamphetamines and narcotic paraphernalia, police said in a statement.

Unprovoked Attack

“Though the victims reported that no hate speech was uttered, investigators are working to determine if racial bias was a motivating factor in the incident,” authorities said.

Officials said the attack happened just before 8:00 a.m. on Monday at Polk and Clay streets where three victims told police they were physically assaulted. Authorities said one of the victims saw an unknown person following two Asian females. The suspect then threw an object that hit the back of one of the two victims and quickly fled.

The witness said the individual later turned around and threatened him, who then used pepper spray to defend himself. The suspect then found a broomstick, approached the witness once more, and threatened him again. The victim then used pepper spray on the attacker again, said police.

Authorities said two other victims were also attacked, a homeless man lying on the sidewalk and a resident who tried to help him. Medical professionals treated two victims at the scene for injuries, the Associated Press reported.

Investigators were looking to determine the identities of the females who fled the scene at the beginning of the incident to take their statements.