Police in suburban Glendale are investigating a series of incidents involving exploding bottles thrown by men from moving vehicles, one of which landed near a Muslim religious leader standing outside a mosque.
No one has been injured in the attacks, but a Muslim civil rights group worried that the incident involving the imam early Monday could have been a hate crime.
Police aren't ruling out a possible hate motive, but said the other incidents had no apparent motive.
Four incidents involving devices commonly known as "bottle bombs" happened during the late night hours within the same half-mile square area between Aug. 3 and 8, said Glendale police spokesman Sgt. Jim Toomey. He said the other three did not involve religious figures, suggesting the attacks may have been random.
"It could go either way," Toomey said Thursday. "It could be local guys just throwing these pop bottle bombs. We really don't know."
The devices are made using common ingredients, not explosives, and violently burst when they are thrown to the ground.
"The victims at the mosque believe that they were specifically targeted, so we'll definitely look into that possibility," Toomey said.
Toomey said detectives had informed the FBI as a matter of routine because there were religious figures involved.
"We are reviewing the incident reports and assisting the Glendale Police," said FBI spokesman Manuel Johnson. "We are trying to determine if any federal crime has been committed and will provide any resources requested or needed."
The imam is one of six Muslim religious leaders who filed a lawsuit against US Airways for removing them from a flight from Minneapolis to Phoenix last year.
The Council on American-Islamic Relations said all six have been previously threatened because of the lawsuit.