Coast Guard crews and firefighters Tuesday morning responded to a Pacifica beach where a man reportedly was swept into the surf by a large wave while he was walking on the rocks, officials said.
At about 7:45 a.m., crews responded by air, water and on the ground, searching for the man, fire officials said.
Bystanders tried to help the man out of the water using a long rope but were unsuccessful. One witness described seeing the man go underwater and not resurface.
The North County Fire Department was being assisted in the search by two Coast Guard helicopters and a Coast Guard life boat.
The waves were coming in at between 12 and 14 feet at the time of the incident, officials said.
No further details were immediately available.