3 dead and 9 injured in shooting at Halloween party in Long Beach, California

A shooter fired into a crowd of several dozen people outside a home in Long Beach, California, late on Tuesday night, killing three men and leaving nine others injured, authorities said.

The victims were at a backyard party in downtown Long Beach, a city south of Los Angeles, when someone began firing "almost indiscriminately" from an alley, the city's police chief Robert Luna said at a press conference.

Luna said it appeared the gathering was of work colleagues who had come together for a Halloween party, and that most of the victims were not Long Beach residents.

The shooter, described as a man of unknown race, is believed to have fled the scene in a dark-colored vehicle, Luna said, adding that it was not clear if others were also involved. He said no one has been detained and that police have been canvassing the neighborhood.

"Why would somebody do something this horrific? We don't know, but I can assure you we're going to work very hard to try and find that out," Luna said. "When you look at this -- and again, this is preliminary -- I don't believe this was just a random act of violence."

The shooting began after 11 p.m on Tuesday night and two police officers responded within a minute of the emergency call, Luna said.

Of the nine people who were wounded, seven were adult females and two were adult males, he said.

"This is not reflective of our community here in Long Beach. This stuff does not happen here," Luna said. "And honestly, it shouldn't happen anywhere else."