“This is the Charm Blow, we are abandoning ship.”

With that message — delivered at 4:20 p.m. Sunday — radio communication with the Coast Guard went dead.

Since then, searchers have been scouring the waters off San Francisco for the reported occupants of a 29-foot sailboat — a couple, their 4-year-old child and the child’s cousin, who the Coast Guard said is younger than 8.

The man had called the Coast Guard an hour earlier to say that the boat had begun taking on water and its electronics were failing, the Coast Guard said. At that time, the boat was some 65 miles (105 kilometers) off Pillar Point.

The four might have boarded a life raft, said the Coast Guard, which appealed to the public for help in identifying the missing seafarers.

“We don’t have a lot of information to go on,” Petty Officer Pam Boehland told CNN. “All we know is that there were those four people on board and the two young children, and we’re hoping that there is still time to save them.”

The focus of the search was 60 to 65 miles off Monterey Bay, said Lt. Heather Lampert, a Coast Guard spokeswoman.

Several aircraft and vessels have joined the search.