NTSB Preliminary Report Says All Crew Members Were Sleeping When California Boat Fire Broke Out

All six crew members on the boat carrying 39 people on a diving excursion were asleep when a massive fire broke out, killing nearly everyone on board, according to a preliminary report.

The National Transportation Safety Board released the report on Thursday, more than one week after the Labor Day weekend fire erupted while the 75-foot Conception was anchored off Santa Cruz Island, California.

The five surviving crew members were asleep behind the wheelhouse on the boat’s uppermost sun deck, while one crew member slept alongside the 33 passengers in the bunkroom on the lower deck, the NTSB said.

The findings come amid reports that the lack of a “roaming night watchman,” someone who is required to be awake at night in order to alert passengers to incidents such as a fire, could mean that the Conception violated safety rules, according to the Los Angeles Times.

Representatives for Truth Aquatics, which owned the Conception, did not immediately respond to PEOPLE’s request for comment.

Investigators spoke with three of the crew members, who all said that no mechanical or electrical issues were reported.

One of the crew members asleep on the sun deck was awakened by a noise and saw a fire at the back of the boat when he got up to investigate, the report said. The flames were coming up from the salon compartment below, which is where the bunkroom’s emergency escape hatch leads.

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He alerted the four other crew members with him, and as the captain radioed a distress message to the Coast Guard, the team made attempts to make their way down to the salon, the report said.

Because the ladder leading down was on fire, they jumped to the main deck, with one crew member breaking his leg in the process.

At this point, the report said, the crew tried to reach the salon through a window.

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“Unable to open the window and overwhelmed by smoke, the crew jumped overboard,” the report said.

After entering the water, two crew members and the captain swam to the back of the boat, got back on board, and opened the hatch to the engine room, where they saw no fire.

They eventually launched a skiff, picked up the two crew members who were still in the water, and were rescued by a nearby boat called the Grape Escape, the report said.

The National Transportation Safety Board said the source of the fire has yet to be determined, though investigators are looking at documents from recent inspections, and have also visited a boat similar in shape and size to the Conception.

The report confirmed that there were two smoke detectors in the bunkroom where the passengers were sleeping.

The Los Angeles Times previously reported that investigators were “taken aback” by the size of the ship’s emergency hatch.

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“It surprised me how small it was and how difficult it was to access,” said Jennifer Homendy, who is overseeing the National Transportation Safety Board’s investigation, adding that she and the investigators also had difficulty finding a light switch.

The final victim from the tragedy was recovered from the water on Wednesday, the Santa Barbara County Sheriff’s Office said.

Officials are still in the process of conducting DNA tests in order to confirm identities of seven of the 34 victims recovered.