When disaster struck the Conception boat around 3:30 a.m Monday, off Santa Cruz Island in California, it happened fast. Flames engulfed the 75-foot diving vessel, and 34 people died.
Now, as authorities have recovered most of the bodies and are working to identify the victims, they're turning their attention to how the fire started.
"Investigators are expected to remain on scene for at least another week," National Transportation Safety Board Member Jennifer Homendy said at a press conference Thursday. She said the preliminary report would be issued 10 days after the accident and that a final report is expected in 12 to 18 months, at which point the NTSB would recommend, if necessary, new safety precautions.
As to what started the blaze, Homendy said investigators are still conducting interviews and creating a timeline.
One of the surviving crew members said he believes the fire initiated from a charging station was full of iPhones and cameras, according to the Los Angeles Times.
Homendy confirmed on Thursday that a large charging station was filled with phones and electronic equipment.
"We are not ruling out any ignition sources, including the electrical system and writing," she said at the press conference. "This is still being investigated."
The boat's designer, Roy Hauser, told the L.A. Times a different theory. He said the "wood-hulled" boat quickly caught fire, leaving the passengers almost no time to escape the flames, possibly because of a battery or charger.
"This had to have been, in my estimation, one of those lithium battery chargers," Hauser told The L.A. Times. "This happened in the belly of the boat. Those people did not have a chance to get out: From stem to stern, that boat was burning."
Homendy said some of the things NTSB investigators are looking at are the adequacy of on-board fire extinguishers as well as smoke detectors. The smoke alarms on the Conception were not connected from the bunkroom to the galley to the bridge, meaning alarms heard by the crew members may not have gone off at the same time as in the bunkroom.
"No crew members heard smoke detectors," Homendy said.
The NTSB said on Thursday that the make and model of the Conception didn't require it to have connected smoke alarms.
Officials told the L.A. Times that they interviewed the crew members and the owner of the company that operated the vessel. None of the crew members failed alcohol or drug tests, according to the NTSB.
The United States Coast Guard suspended its search for survivors about 23 hours after being called to the scene.
"We are also grateful to the heroic first responders who have been working around the clock on search, recovery and identification efforts," California Gov. Gavin Newsom said in a statement Thursday. "The Governor’s Office of Emergency Services is working closely with local first responders to provide assistance and is in a unified command to ensure cross-jurisdictional coordination. California is committed to assisting in recovery efforts and the investigation, however possible. Based on the findings of the investigation, the state will take action to prevent horrific boat fires like this in the future."
Dominic Selga previously told ABC News that his three sisters, mother and stepfather were among those who died.
"Just thinking about that is difficult," Selga said. "Being burned alive, burning while drowning, while inhaling smoke, that's insane."
Many of the other victims have yet to be identified.
The danger of lithium-ion batteries is something federal agencies have tried to tackle in recent years. Airlines have long warned about their potential to explode, which is why they ask passengers to carry on laptops and phones.