A SCUBA DIVE boat sank amid intense flames early Monday off the coast of Southern California and 34 passengers were unaccounted for, the US Coast Guard said.

Fire crews in helicopters, small boats and a Coast Guard cutter spent hours battling the fierce pre-dawn fire on the 75-foot  Conception, which had been on a diving excursion around Santa Cruz Island. 

But the blaze and intense heat prevented them from breaching the vessel’s hull to search for survivors before the craft sank, the Coast Guard said.

Five Conception crew members were awake and jumped into the water when flames burst out around 3.15 am (10.15pm Irish time), Coast Guard Captain Monica Rochester told reporters in a televised briefing. 

The five were rescued by people on a pleasure craft called the Grape Escape, Rochester said. 

She said it was unclear whether the Conception’s crew had been able to try to rescue any passengers, all of whom were believed to have been sleeping in a bunk cabin below decks.

She said 34 people — not the 33 reported earlier by the Coast Guard — were unaccounted for when the Conception sank 20 yards (meters) offshore, leaving only its bow exposed.

“I’m unaware of any survivors at this time,” Coast Guard Petty Officer Aaron Bemis told CNN earlier, adding that it was too soon to confirm casualties.

A shoreline search

Rochester said the Coast Guard was still in “response phase” — meaning search and rescue efforts were continuing, primarily through a shoreline search for possible survivors.

She said the Conception, which was launched in 1981 by a Santa Barbara-based company called Truth Aquatics, “has been in full compliance” with safety regulations, and that its owner was cooperating with investigators.

Asked whether there had been an explosion on board or a slow-developing fire, Rochester said that “the only Mayday call we received was the vessel was engulfed in flames.”

Bemis said the fire was put out multiple times but flared back up, apparently because of the amount of fuel in the vessel, which could carry up to 1,600 gallons, according to the company website.

Bill Nash, a spokesperson for Ventura County, told CNN many people were feared dead. Crews from that county and from Santa Barbara County had joined the Coast Guard in battling the fire.

“It’s a large boat, and we know we have numerous fatalities,” Nash said.

The Truth Aquatics website said the Conception, listed as having bunks for up to 46 people, had been scheduled to return Monday from a three-day trip after visiting several diving spots around Santa Cruz Island.

The area is popular for a variety of water and outdoor sports.

- © AFP 2019.