Eight people have died after two boats capsized off the coast of California, emergency officials have said, with officials suspecting that the craft were being used by people smugglers.

San Diego Fire and Rescue officials received a 911 emergency call at around 11.30pm on Saturday night local time.

The caller reported that she was on a panga boat – a small fishing craft powered by an outboard motor and often used by people smugglers – with 15 people which had made it to Black’s Beach, just north of the city.

“The woman who called stated that the boat that overturned had 15 people on it, but that was just an estimate,” according to Coast guard petty officer Richard Brahm.

Rescuers set off to the beach after using GPS coordinates to locate the woman’s phone and arrived to find two overturned boats there and bodies spread across hundreds of metres of the coast.

Several crews searched the area from the air and in the water but thick fog overnight hampered their efforts. The search continued on Sunday.

Daniel Eddy, San Diego Fire Rescue’s deputy chief of operations, said debris could be found all along Black’s Beach.

The beach is jointly owned by the city of San Diego and the state of California. The stretch of sand is also known as Torrey Pines City Beach and Torrey Pines State Beach and is considered one of the most secluded beaches in the area.

Coast guard petty officer Eddie Berrios confirmed eight people died and teams were searching for at least seven more. Pangas are regularly used by people smugglers in the area: San Diego is just miles from the border with Mexico.