"This isn't a day that we wanted to wake up to for Labor Day, and it's a very tragic event", Rochester said at a press conference.
According to media reports, a total of 39 people - 33 passengers and six crew - were on the boat when it was engulfed in flames.
The four bodies were identified as two adult males and two adult females, Brown told reporters.
"This is probably the worst-case scenario you can possibly have", Brown said.
Dave Reid, who runs an underwater camera manufacturing business with his wife, Terry Schuller, and who has traveled on the Conception and two other boats in Truth Aquatics' fleet, said he considered all three among the best and safest dive-boats around.
After borrowing clothes from the Hansens, some crew members headed back toward the Conception to look for survivors without luck, Hansen said.
The boat was scheduled for a three-day $665 diving excursion "to explore the pinnacles of San Miguel Island" that departed Saturday morning and was due back Monday evening, according to a Truth Aquatics schedule.
"We are looking for bodies now", said Santa Barbara Fire Department spokeswoman Amber Anderson. The five survivors are all crew members. With the help of a nearby pleasure craft called The Grape Escape, they were able to make it to safety.
"We launched that boat knowing that the vessel was on fire, lots of people aboard", he told The Associated Press.
A woman who came to the harbor said, "My son was on that boat".
A growing memorial has been established at the Santa Barbara Harbor where the Conception would normally be docked.
Lopez says "it's just hard for them to process all of this".
Authorities said the explosions reported by witnesses likely were scuba or propane tanks that burst in the heat of the fire, rather than the cause of the fire itself.
One talked about celebrating a 17-year-old girl's birthday hours before the fire. When they arrived, they found "at least 30 passengers on board and (the boat was) fully involved in flames", Alldredge said.
Santa Barbara City Search and Rescue along with Santa Barbara Sheriff's officers move a recovered body on the dock at Santa Barbara Harbor in Santa Barbara, Calif., Monday, Sept. 2, 2019.
Next time he went out in a similar vessel, he said, he would think about the layout of a boat and how he would escape if he had to.
The wreckage is upside down, and authorities plan to stabilize the boat Tuesday so dive teams can investigate the scene and recover additional remains. No one is ever locked into that deck, he said, but coming up to the top deck to get off the boat requires negotiating a narrow stairway with only one exit. They would have realized that the fire had grown to the point that you couldn't do anything but jump overboard from a few stories above to save themselves.