Los Angeles (CNN) Crew members of the dive boat that was consumed in flames off the California coast on Labor Day told investigators they tried to rescue the 34 people who were still on board in the inferno, the National Transportation Safety Board said Thursday.

Of the 39 people aboard the 75-foot dive boat Conception, only five crew members, including the captain, were found alive.

The others, who were in the lower sleeping deck, likely got trapped when the roaring blaze blocked their escape routes, authorities have said. The crew was on the upper wheelhouse deck.

"What's emerging from the interviews, and these are individual interviews with NTSB investigators, is a harrowing story of the moments before the fire erupted on the vessel," NTSB board member Jennifer Homendy said.

One crew member said he awoke to a noise and left his bunk to see flames erupting from the galley area below, Homendy said. The galley was above the sleeping quarters of the guests

The crew members tried to get down the ladder from the galley to the sleeping area but it was engulfed in flames. They were forced to go down to the main deck from the bridge, and one of them broke their leg getting down, according to Homendy.

'The crew had to jump from the boat'

A chart showing the layout of the bunk room on the website of the company that owns the Conception, Truth Aquatics, appears to show the main way in and out of the bunk room is through the galley.

After reaching the main deck, the crew members went to the double doors of the galley to try to get to the passengers, but it too was engulfed in flames, NTSB investigators were told.

They then tried and failed to get in through a window in the front of the vessel, Homendy said at the press conference.

"At that point, due to heat, flames and smoke, the crew had to jump from the boat," Homendy said.

Some crew members swam to a skiff on the back of the boat, picked up the other crew and they made their way to a nearby vessel to call 911, Homendy said.

"At that point, they left the vessel and turned back to the Conception in the skiff to try to rescue any survivors," she said.

"What I shared with you is from what we heard from them," Homendy said. "So now it's our job to take that and develop a timeline."

The NTSB will also evaluate whether there were "issues with evacuation or responses" or "escape survival factors," she said.

The NTSB also interviewed the owner operator of the dive boat, Homendy said, without giving any details.

Thirty-three bodies have been recovered, and one remains missing, the Santa Barbara County Sheriff's Office's said.

Safety concerns

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After investigating a similar boat owned by the same company, Homendy told CNN she has several safety concerns, including whether there is proper equipment for detecting and suppressing fire.

On the similar boat, the Vision, smoke alarms were not connected throughout the boat.

"We're looking into the adequacy of smoke detectors and were there enough fire extinguishers," Homendy said.

The escape hatch in the lower bunk level on the Vision was small, difficult to see, access and maneuver, she said.

In trying to pinpoint where the fire started, investigators are looking at the main deck and galley now, Homendy said.

"But we are not closing out any possibilities, from the engine room to the passenger compartment," she said.

"We are looking at the engineering, the wiring," Homendy said. "We are aware that there was a lot of gear on board with the cameras and the crew, cameras, phones, extra batteries. And chargers."

'Regulations are written in blood'

Diver Dale Sheckler said he has taken well over 100 trips on the Conception since 1985 and reported seeing several stations with power strips charging phones, laptops, cameras, underwater lights and more.

"The main charging station would be above the bunk beds in the galley," Sheckler said. "It was a little tight to find space to charge."

Still, any theory that the fire started at a charging station is "conjecture," he said.

"The Conception always has been a top notch, well-run operation," Sheckler said.

The Labor Day disaster may well spark changes in regulations of commercial dive boats and related vessels, said retired US Coast Guard Capt. Kyle McAvoy, an expert with Robson Forensic, who specializes in watercraft safety and accidents.

"A lot of regulatory and policy and safety initiatives are driven by tragic events such as this," McAvoy told CNN. "The expression is that a lot of regulations are written in blood."