(Adds statement from Federal Protective Service; details from source)
By Steve Gorman
LOS ANGELES, July 14 (Reuters) - Four people have been arrested and a Homeland Security officer is under investigation for firing his weapon during a weekend scuffle between pro-Israel demonstrators and Palestinian supporters outside the Federal Building in Los Angeles.
The altercation Sunday evening grew out of a shouting match between the occupants of two vehicles that escalated when several people from one vehicle were assaulted by suspects in the other, the Los Angeles County Sheriff's Office said.
An officer of the Federal Protective Service, an agency of the U.S. Department of Homeland Security, who witnessed the assault intervened and fired his weapon, but no one was hit by gunfire or otherwise injured, Sheriff's Sergeant Carmen Arballo said.
She said four suspects were arrested. According to sheriff's officials, the four were booked on suspicion of assault with a deadly weapon after some of those involved in the melee were seen brandishing wooden poles, City News Service reported.
A Federal Protective Service spokeswoman in Washington, Jacqueline Yost, said the officer fired one shot from his service weapon in an attempt to stop the four suspects as they were trying to flee the scene in a vehicle.
The officer has been placed on paid administrative leave pending a review of the incident by his agency, and an investigation by the Los Angeles sheriff's office, Yost said.
The clash erupted when Palestinian supporters drove up to a group of pro-Israel demonstrators and thrust a Palestinian flag out the window of their truck, according to a law enforcement source who was familiar with how events unfolded but was not authorized to comment on the record about it.
Pro-Israel demonstrators then grabbed the flag and stomped on it, leading to a brawl as the Palestinian supporters got out of their truck and one was stomped and kicked while bending down to retrieve the flag, the source said.
The confrontation occurred at the end of a rally by an estimated 500 demonstrators in support of Israel's bombardment of the Gaza Strip in retaliation for rockets fired into Israel by Palestinian militants. A similar protest had been held at the same location on Saturday by Palestinian supporters condemning Israeli bombing of Gaza. (Reporting by Steve Gorman; Editing by Jim Loney and Eric Walsh)