The Santa Barbara County Fire Department said the vessel that caught fire early Monday is a 75-foot dive boat named Conception, which was based in Santa Barbara Harbor.
The vessel caught fire while anchored off Santa Cruz Island early Monday, the Fire Department said.
Five people were rescued and 34 remained missing, the agency said in a 7:09 a.m. tweet.
Conception had a maximum capacity of 46 people and operated year-round, according to the website California Diving News. It launched in 1981, the website said.
Ventura County and U.S. Coast Guard officials released conflicting details on a fiery dive boat incident near Santa Cruz Island early Monday.
The Ventura County Fire Department told Diversity News 34 people died, but U.S. Coast Guard Petty Officer 3rd Class Aidan Cooney said he could not confirm that.
The two agencies are handling the incident.
The Fire Department said its crews responded to the scene at 3:28 a.m. Thirty-four individuals were aboard the boat and five people have been taken to a hospital, Cooney said.
In an earlier tweet, at 5:43 a.m., the Coast Guard said "a group of crew members has been rescued (one with minor injuries) and efforts continue to evacuate the remaining passengers."
The Fire Department released images from the scene showing the boat engulfed in flames.