WARNING: This story contains disturbing content.
The Coast Guard couldn’t hear much when a mayday call came in about a scuba diving boat on fire on the north side of Santa Cruz Island on Monday morning.
They could, however, make out one cry: “I can’t breathe.”
The call informed the Coast Guard about a deadly boat fire that left eight dead, five rescued and others missing as of Monday afternoon.
WATCH: Five rescued, 34 missing in California boat fire: U.S. Coast Guard
The call came in just after 3 a.m. from the Conception, a diving vessel measuring 75 feet.
The caller reached the Coast Guard Centre in Los Angeles.
“Mayday mayday mayday,” the caller said.
“What is your position and number of persons on board,” the Coast Guard dispatch responded.
“I can’t breathe… 39 POB,” the caller said.
That was enough to tell the Coast Guard there were 39 people on the vessel, though officials later said there were 38 aboard.
WATCH: U.S. Coast Guard working to rescue occupants from burning boat in California
Bodies found in the incident had injuries that were consistent with drowning, said Lt. Cmdr. Matthew Kroll.
Officials determined that the boat was already completely engulfed in a blaze when the mayday call came through.
As CNN reported, the Coast Guard dispatcher asked a crew member from the Conception whether anyone was locked on the boat.
The dispatcher asked, “Can you get back onboard and unlock the boat?”
The Coast Guard also asked whether the boat had an escape hatch that passengers could use.
Authorities rescued five people who had been sleeping on the boat’s top deck. They are believed to have jumped off the vessel.
The boat’s sleeping quarters were below the deck, Ventura County public information officer Bill Nash told ABC News.
The fire’s cause remains a mystery.