VENTURA, Calif. — At least 4 people are confirmed to be dead after a boat caught fire Monday morning off the Southern California coast.

There were 39 people on the 75-foot commercial diving vessel, the Conception, that caught fire around 3:30 a.m. near Santa Cruz Island, the U.S. Coast Guard said. The boat has since sunk.

Five crew members who were awake at the time evacuated quickly, said U.S. Coast Guard Lt. Commander Matthew Kroll.

"We can only identify them as two adult makes and two adult females," Santa Barbara Sheriff Bill Brown said, speaking at a press conference on Monday afternoon.

The sheriff also indicated that rescue teams had located four additional bodies on the ocean floor near the boat's wreckage. But due to the instability of the wreck, teams are currently unable to retrieve them.

Authorities said death investigations will be handled by the Santa Barbara County Coroner.

Santa Cruz Island is part of the Channel Islands near Ventura. The group was on a diving trip for the Labor Day weekend. 

"Our hearts are with the families and loved ones affected by this tragic incident," tweeted Governor Gavin Newsom. "As we wait to hear more, we are eternally grateful for our heroic first responders that are on site — working to ensure every individual is found."

As of Monday afternoon, a search was still underway for possible survivors.

"This isn't a day that we wanted to wake up to for Labor Day, we will search all through the night and into the morning, but I think we should all be prepared to move into the worst outcome," said Coast Guard Captain Monica L. Rochester.