34 missing in boat fire off California coast

(CNN) There are fatalities on a boat that caught fire early Monday off the coast of Santa Cruz Island in Southern California, and authorities are working to extinguish the blaze, Ventura County spokesman Bill Nash said.

The dive boat was carrying at least 34 people, officials said, though Nash said he did not have the exact number of casualties.

The boat is about 20 miles off the coast, in the Channel Islands National Park. While Nash wasn’t certain to which island the boat was nearest, the US Coast Guard reported it was near Santa Cruz Island.

Authorities responded to a report of a boat fire about 3:30 a.m. (6:30 a.m. ET), the Ventura County Fire Department said. They arrived and began rescuing passengers from the 75-foot vessel.

The cause of the blaze was not immediately clear.

The Coast Guard said in a tweet that it had “launched multiple rescue assets along with assets from local agencies to assist more than 30 people in distress on a 75ft boat near Santa Cruz Island.”

An update said, “There were 34 people on board and the Coast Guard has rescued five.” It was not clear if the five were included in the 34 on board.

A group of crew members, one with minor injuries, were among the rescued, the Coast Guard said.

The boat, named “Conception,” is based out of Santa Barbara Harbor, according to harbor patrol officer Nathan Alldredge.

Authorities responded to a call for fire and rescue support in the Platts Harbor area of Santa Cruz Island before 4 a.m., he said. When they arrived, they found “at least 30 passengers on board and (the boat was) fully involved in flames,” Alldredge said.

According to Truth Aquatics website, which conducts boat charters, Conception left Saturday on a three-day cruise and was scheduled to return today.

This is a developing story. Please check back for more details.

CNN’s Eliott C. McLaughlin and Karan Olson contributed to this report.