The California diving boat that killed 34 people when it burst into flames appeared to have serious safety deficiencies, a preliminary investigation has found.

Among the problems aboard the Conception was the lack of a “roaming night watchman” whose job is to remain alert and notify passengers if a fire or another danger was to occur, several law enforcement sources familiar with the probe told The Los Angeles Times.

Investigators are also questioning whether the crew aboard the vessel was sufficiently trained and whether the passengers received a full safety briefing, the sources — who wished to remain anonymous as they did not have approval to comment about the cause — told the paper.

A Coast Guard spokesman told the outlet that the investigation is wide-ranging, but declined to comment further.

While authorities have not stated that the deaths — or the fire itself — resulted from any kind of criminal wrongdoing, prosecutors from the US attorney’s office in Los Angeles were on hand Thursday to help investigators, according to the paper.

Hours before the blaze broke out, the passengers had performed a night dive, a source familiar with the crew’s actions told the outlet.

A crew member had been fixing up items in the galley and mess area — and then checked to make sure the stove was cold and no flammable items were scattered around before going upstairs to the wheelhouse around 2:35 a.m., the source said.

Sometime between then and 3:15 a.m., the crew member reported hearing a sound that he thought was someone who had tripped, the source said. But when he made his way to the middle level, he saw the fire, and the flames prevented him from making his way into the galley, according to the source.

Later, the crew suspected that the blaze broke out in the seating area of the galley, the source told the paper.

No crew members reported hearing an alarm go off, according to the source.

Jennifer Homendy, who is overseeing the National Transportation Safety Board’s investigation, told the Times that the smoke alarm aboard the ship is one that could be bought at Home Depot.

Homendy told the Times she toured another boat Wednesday named the Vision, which is slightly larger than the Conception, but has a similar layout.

That boat, too, had one smoke alarm that was not hooked up to a centralized alarm system — which was not required at the time the vessels were built, she told the paper.

The NTSB is also assessing the wiring and electrical systems in place on the boat, as there were many pieces of photography equipment and extra batteries charging aboard the Conception, the paper reported.

“Did that provide the ignition source?” Homendy said. “But we’re not closing in on that. We’re not ruling out anything at this point.”

Authorities have said that the vessel’s exit, as well as an escape hatch that opens near the dive deck, was blocked by the flames, according to the report.

Additionally, the boat was not at its full capacity and could have held additional passengers, Homendy told the paper, adding that the NTSB is probing whether “there needs to be new safety standards to make sure this does not happen again.”

“I definitely have concerns about the ability of those passengers being able to evacuate during a fire,” Homendy said.