Science teacher and his daughter, an adventurous marine biologist and a family of five among 34 killed, US media report.

Divers have recovered the bodies of all but one of the 34 people killed when the scuba tour boat they were sleeping on off Santa Cruz Island, California, erupted into flames early this week, officials said on Wednesday.

The charred wreckage of the Conception now rests 18 metres below the surface. Divers were still actively searching for the remains of one person, said Amber Anderson of the Santa Barbara County Sheriff’s Office.

The boat’s captain and four crew members were above deck when the blaze broke out early on Monday morning and escaped in an inflatable boat.

A crew member who was killed was apparently sleeping below deck with the passengers at the time.

In this photo provided by the Santa Barbara County Fire Department, a dive boat is engulfed in flames after a deadly fire broke out on board the commercial scuba diving vessel off the Southern California Coast, [Handout/Santa Barbara County Fire Department/AP Photo]

None of the victims has been officially identified yet. But Santa Barbara Sheriff Bill Brown said he had heard anecdotally that those who died ranged in age from teenagers to people in their 60s.

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US media have also reported that the dead include high school students, a science teacher and his daughter, an adventurous marine biologist and a family of five celebrating a birthday.

Investigation launched

Federal safety investigators on Tuesday promised an exhaustive investigation of the fire.

National Transportation Safety Board member Jennifer Homendy said 16 investigators were already assigned to the investigation, including specialists in operations, engineering, survival factors and fire analysis. A press conference is scheduled for Wednesday afternoon.

In this photo released by the Ventura County Fire Department, firefighters attempt to extinguish a fire on a boat off the coast of Santa Cruz Island, California [Handout/Ventura County Fire Department/AFP]

The investigators will collect all perishable evidence while on scene for at least a week, she said, but the Conception would remain on the ocean floor until a site survey had been completed.

Coast Guard records show the boat’s owners quickly addressed all safety violations over the past five years.