LOS ANGELES (Reuters) - The police on Saturday were investigating what prompted a man dressed in black to embark on a string of shootings in the California beach community of Santa Monica, killing four people before the police gunned him down in a community college library.

Los Angeles county's coroner department identified one of the four dead as Mr Carlos Navarro Franco, 68, of west Los Angeles, who was driving a sports utility vehicle at a staff parking lot of Santa Monica College when he was shot on Friday.

The police say the carnage began at a home east of the college, where the gunman shot two people dead before apparently torching the home. The Los Angeles Times, citing law enforcement sources, reported that the first two victims were believed to be the gunman's father and brother.

The police have not publicly identified the shooter.

After leaving the home, the gunman carjacked a woman and ordered her to drive, Santa Monica Police sergeant Richard Lewis said on Friday. Along the way he fired at least several rounds at a city bus, wounding three people.

Arriving at the college, the gunman opened fire on a red sports utility vehicle in a staff parking lot, killing Mr Franco and critically wounding his passenger, Sgt Lewis said.

The gunman, who was armed with an AR-15 style rifle and at least one handgun, then shot and killed another victim at the college before he was slain in an exchange of gunfire with the police, Sgt Lewis said.

The police were expected to hold a news conference at midday local time on Saturday. The main campus of Santa Monica College remained closed due to the ongoing criminal investigation, according to the school's website.

The shooting rampage unfolded just a few miles from where President Barack Obama was speaking at a political fundraiser elsewhere in Santa Monica, west of Los Angeles.

The bloodshed did not appear to be related to Mr Obama's visit, and the Secret Service called it a "local police matter". The killing spree marked the latest in string of high-profile mass shootings, including an attack last December in Connecticut that killed 20 children and six adults at an elementary school and a shooting last July at a suburban Denver movie theater that left 12 people dead.

Those attacks have helped reignite a national debate over gun violence in America that spurred Mr Obama and his fellow Democrats to push for expanded background checks for gun buyers - an initiative defeated in the US Senate.

Mr Obama on Friday had been attending a fundraising event at the Santa Monica home of former News Corp president Peter Chernin at about the time of the shooting and had just finished his remarks. He made no mention of the incident.

A Secret Service spokesman in Washington said: "We are aware of the incident and it is not impacting the visit. It's a local police matter at this point."

Mr Obama's departure from Los Angeles was rerouted to avoid the scene, a White House press secretary said.