A preliminary investigation into the California boat fire that killed 34 people suggests serious safety violations.

The Conception caught fire early Labour Day morning off the coast of southern California. Only five crew members survived. None of 33 passengers, who had signed up for a scuba trip on the boat, lived.

Now, law enforcement officials say crucial safety precautions were lacking, including a “roaming night watchmen,” who’s required to be awake and alert passengers to danger.

Officials are also searching for the boat’s maintenance and inspection records, which the Coast Guard said were up to date.

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Among other concerns, investigators are looking into whether or not the crew was adequately trained, The Los Angeles Times reports.

Though authorities have not suggested the fire was the result of criminal wrongdoing, prosecutors prosecutors from the US attorney’s office in Los Angeles were at the scene on Thursday, assisting investigators. The probe could reportedly take months to complete.

Authorities have recovered 33 bodies from the vessel, now 60 feet below the surface. Divers are still searching for remains.

Jennifer Homendy of the National Transportation Safety Board said surviving crew members have told authorities the fire was too intense to attempt a rescue of those trapped.

“What’s emerging from the interviews is a harrowing story of the last few minutes before the boat was engulfed in flames,” Ms Homendy said. “They felt that they had done what they could do in a very panicked situation.”

Survivors swam to a nearby fishing boat after they escaped the fire, according to Buzzfeed News.