Four dead and 29 missing as boat sinks after bursting into flames off California coast

Four people have been killed and 29 are missing people after a diving boat burst into flames and sank off the coast of California early Monday morning, officials have confirmed.

The fire is thought to have broken out just before 5am (11am GMT) near Santa Cruz Island, close to Los Angeles.

Five crew members managed to escape the vessel, one of whom is being treated for a broken leg, reports from the area said.

It is understood that the crew members were sleeping on the top deck of the boat when the fire broke out.

Twenty-nine people on board have not been accounted for, according to the U.S. Coast Guard.

The vessel sank 20 yards off-shore as fire department crews were fighting the fire, according to the statement.

Ventura County firefighters responding to a boat fire off the coast of southern California. (AP)

Emergency services are at the scene and are attempting to put out the fire, which "fully engulfed" the boat.

The US Coast Guard responded with two helicopters, two 45-foot Swift boats and an 87-foot cutter.

“The Coast Guard has launched multiple rescue assets along with assets from local agencies to assist more than 30 people in distress on a 75ft boat near Santa Cruz Island,” the Coast Guard tweeted.

Ventura County officials say multiple people have died but the US Coast Guard has yet to confirm fatalities.

Jen Buesinger Sperry, a Good Day LA reporter, is calling it a “mass fatality” incident.

The boat, a scuba diving vessel, is named “Conception,” Santa Barbara Harbor Patrol Officer Nathan Alldredge told the New York Times.

The US Coast Guard said it has launched several boats to help over two dozen people "in distress" off the coast of southern California. (Ventura County Fire Department/AP)

Coast Guard senior chief Aaron Bemis told CNN the fire on the boat keeps re-flashing, hampering efforts to board the boat and look for survivors.

“Multiple Coast Guard and local Ventura County Fire Department assets on scene, but we're not able to yet breach the hull and see if there's any survivors at this point,” Mr Bemis said.

“I'm unaware of any survivors at this time, and I'm also no confirmed casualties at this time. It's too early to tell.”

He added: "It's a 75-ft commercial dive vessel that reportedly had 39 people on board. The five crew members able to disembark because they were in the main cabin. The passengers were below decks.

"The report we got was they were trapped by the fire. The fire was so intense that even after it was put out, we're not able to actually embark the vessel and, you know, look for survivors at this point. It's still ongoing."

Watch the latest videos from Yahoo UK