CALIFORNIA, Sept. 2 (CGTN) -- Twenty-five people were killed and nine were still missing after a diving boat caught fire off Santa Cruz Island in southern California in the U.S. on Monday, AP reported citing the coast guard.

Earlier, police said they had recovered four bodies, while four more were discovered on the ocean floor near the vessel. Their identities have yet to be confirmed.

Five people have been rescued so far and boats, diving teams and aircraft were still searching for the missing people.

According to the authorities, the boat named "Conception" was on a three-day diving excursion around Santa Cruz Island, west of Santa Barbara, which was due to end on Tuesday morning.

The five rescued were crew members, who were awake and jumped into the water when flames burst out at around 3:15 a.m. local time (1015 GMT), Coast Guard Captain Monica Rochester said, putting the total number of people aboard the boat at 39.

The passengers however were believed to have been sleeping when the fire erupted and were trapped below deck by the roaring blaze.

The coast guard said the fire and heat prevented rescuers from breaching the vessel's hull to search for survivors before the craft sank, and a dense fog further complicated rescue efforts.

The vessel had a crowded cabin with three-high bunks below deck and sank 20 meters off the island's northern shore, leaving only its bow exposed.