U.S. investigators on Thursday were examining potential ignition sources of a deadly fire on a scuba diving boat, including electronics aboard the vessel where 34 people were killed off the coast of Southern California.
Investigators know photography equipment, batteries and other electronics were stored and plugged in on the Conception, said Jennifer Homendy, a member of the National Transportation Safety Board.
"We are not ruling anything out at this point," she said.
Homendy also said she had inspected a vessel similar to the Conception and was concerned about the accessibility of its emergency exit hatch and possible difficulties getting to safety.
The victims died after flames above deck blocked the one stairway and the hatch leading from sleeping bunks to the upper decks and gave those below virtually no chance of getting out, authorities have said.
The Conception had been in full compliance with Coast Guard regulations, officials said.
The federal investigation continued as divers resumed a search for the last victim who remained missing. Divers have pulled 33 bodies from the seabed and the charred wreckage of the sunken, overturned boat.
California Gov. Gavin Newsom identified two of the victims as Adrian Dahood-Fritz and her husband Andrew Fritz. Dahood-Fritz had worked for the California Natural Resources Agency's Ocean Protection Council since April as a senior environmental scientist.
"Adrian led the state's efforts to manage California's network of marine protected areas, and she cared deeply about the ocean and biodiversity," Newsom said in a statement. "She embodied marine conservation and was a highly accomplished and respected scientific researcher."
The other victims included two high schoolers, a hairdresser, marine biologist, software engineers, special effects designer for Disney, nature photographer, nurse and family of five celebrating a birthday.
Their common love of scuba diving led them to the ruggedly beautiful coastline of the Channel Islands for a three-day excursion planned through Labor Day.
Five crew members, including the captain, were above deck and managed to escape. Officials said they expected to interview the captain Thursday.
The only crew member to die was Allie Kurtz, 26, who quit her corporate job at Paramount Pictures to work on dive boats. Kurtz, who grew up in Illinois, had recently been promoted to deckhand.
"Her love was just always, always the water," Kurtz's grandmother, Doris Lapporte, 71, said. "She would joke, 'I am going to be a pirate one day.'"
Four crew members were given tests for alcohol, which were negative, and all five survivors had drug tests and the results are pending, Homendy said.
The Conception wasn't required by federal regulations to have fire sprinklers aboard, according to the U.S. Coast Guard.
Other California divers have said Truth Aquatics, which owned the Conception, and its captains were very safety-conscious and the tragedy shocked the industry.
Cheryl Babineau, owner of Pro Scuba Dive Center in Scotts Valley, California, and a certified diver for 45 years, said boat passengers sometimes tune out when the captain and crewmembers review safety instructions for a dive trip. She expects that will change.
"I think now people will pay a lot more attention," she said.
The boat's owner and others were interviewed for hours as the National Transportation Safety Board investigated the fire, Homendy has said.
Those killed included Apple engineer Steve Salika and his wife, Diana Adamic, who went on the trip with their daughter Tia Salika to celebrate her 17th birthday, company senior vice president Deirdre O'Brien told The Mercury News newspaper. Apple colleague Dan Garcia joined them.
Tia was with Berenic Felipe, a fellow student at Pacific Collegiate Charter School in Santa Cruz, according to a letter sent to the school community obtained by NBC News.
Also aboard was visual effects designer Charles McIlvain, who was known for his work on films such as "Spider-Man" and "Green Lantern."
Lisa Fiedler was a 52-year-old hairdresser and photographer from Mill Valley, north of San Francisco, her mother, Nancy Fiedler, told San Francisco's ABC affiliate, KGO television.
San Francisco-based education platform Brilliant confirmed that senior software engineer Carrie McLaughlin and Kristian Takvam, vice president of engineering, were aboard.