Many of the 39 people aboard the 75-foot Conception were thought to be sleeping below deck when the fire broke out about 3:15 a.m. Monday.
The vessel was anchored about 20 yards off Santa Cruz Island when the charter became engulfed in flames, said Mike Eliason, spokesman for the Santa Barbara County Fire Department. The victims have yet to be identified.
As of early Tuesday, authorities said 25 bodies had been located, nine were still missing and five were rescued. Of those who were recovered, 11 of the victims were females and nine were males, Santa Barbara County Sheriff Bill Brown said at a press conference Tuesday morning. He said four to six others have been located by divers but have not yet been recovered due to unsafe conditions around the boat.
"It is never an easy decision to suspend search efforts," said Capt. Monica Rochester, with the U.S. Coast Guard. "We know that this is a very difficult time for families and friends of the victims. We have suspended the search efforts due to no additional individuals having been witnessed entering the water."
Most of the recovered victims, including those who suffered "extreme thermal damage," need to be identified by DNA analysis and officials are collecting samples from family members, Brown said.
At the marina in Santa Barbara, a memorial featuring a candle for each of the 34 victims is growing. Family members and friends of the victims are gathering to mourn and to seek information.
"She's gone," said Claire, a woman who said her older sister was a member of the crew and did not survive. "She's not going to come back. I texted her yesterday. Even though I knew she wasn't going to respond, just hoping that maybe there was a slight chance maybe she would respond."
"She unfortunately left this Earth doing something she loved. She was an amazing person. She had the biggest heart. She was my role model, my big sister. She was everything to me. And she's just gone now."
After the fire broke out early Monday, five of the six crew members were able to jump overboard and escape on a dingy. Those five crew members had been awake and on the bridge of the boat when the flames broke out.
They were pulled from the water after banging on Bob and Shirley Hansen's pleasure craft. The crew told the Hansens one of the crew members had a girlfriend on board the engulfed boat. One of the rescued individuals suffered a broken leg.
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The Hansens say they observed flames and plumes of smoke billowing out of the vessel as several small explosions went off every few minutes, which they believe were caused by the dive tanks.
"It was so overwhelming to come out and see these men there, and look over and see the extent of the fire," Shirley Hansen said. "The flames were shooting up into the sky."
The Hansens were told by the crew that there were three birthday parties on board the boat, including one for a 17-year-old.
"When they opened the galley door, which was the main exit for those people sleeping down below, they said there was so much fire in there that even the roof tiles were on fire and falling from the ceiling already," Bob Hansen said. "So there was no access for them to get to the 34 guests that were below."
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Of the 25 bodies that have been located, 20 were physically recovered. The remaining five have been located but cannot be recovered because of unsafe conditions under the Conception, Coast Guard Lt. Cmdr Matthew Kroll told the Associated Press.
"It was horrific. I'd never seen such a thing," Bob Hansen said. "There wasn't a part that wasn't burning. Everything was burning on it."
The Conception sank in 64 feet of water as firefighters were battling the blaze, leaving the charter protruding from the water, officials said.
Santa Barbara County Sheriff Bill Brown said it may take some time to identify the deceased because of the condition of the bodies and because they don't have a full manifest of everyone who was on board. It will require DNA testing to identify most of the remains.
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Brown said the situation - a boat fire in the middle of the night, with people trapped at the bottom of a ship - is one of the most difficult operations for rescue crews.
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"This is probably the worst-case scenario you could possibly have," Brown said. "Fire is the scourge of any ship."
The boat trip was touted as a Labor Day weekend dive excursion that started on Aug. 31 and was scheduled to return Sept. 3. There were six crew members on board and one of them is among the missing.
The boat was in a remote location and there was limited firefighting capability.
"You couldn't ask for a worse situation," Brown said.
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Family members looking for information about their loved ones are asked to call 833-688-5551. A family assistance center was established at Earl Warren Showgrounds, 3400 Calle Real, Santa Barbara. For information, call 805-696-1188.
The cause of the fire remains under investigation. Officials said it appears to have been an accident and there are no indications of an intentional act, but the official investigation will take time.
The Associated Press contributed to this story.