Someone shot BB gun pellets and threw an object into the office located at 6700 block of South Centinela Avenue in Los Angeles. The incident happened just four days before Obama's scheduled visit to the city on Monday.

　　No staffers were in the office at the time of the shooting, the police said. But it was not disclosed whether the shooting was captured on surveillance video.

　　An investigation involving several law enforcement agencies has been initiated.

　　The White House announced earlier that Obama is due to visit Los Angeles Monday to raise money for what is expected to be a bruising 2012 re-election campaign.

　　He was supposed to stay overnight in Los Angeles and depart on Tuesday morning.

　　The White House did not say whether the president will change his schedule.