At least eight people have died after two boats capsized off the California coast, emergency services have said.
A search began after the boats got in trouble off Black’s Beach, San Diego.
A 911 caller told emergency services she had been on a boat with eight people that made it to shore, but another vessel, carrying eight to 10 people, had capsized.
San Diego Lifeguard chief James Gartland called it one of the state’s worst maritime smuggling tragedies.
Officials said they did not know the nationalities of the victims but they were all adults.
Emergency responders from several agencies found two overturned boats with bodies spread over an area of 400 yards (366m), and a search operation continued into Sunday morning.
It was unclear what caused the incident but Mr Gartland described the area as “hazardous” due to sand bars and in-shore rip currents.
Rescuers did not find any survivors, but some may have left the beach before the emergency services arrived, he suggested.
James Spitler, a sector commander for the San Diego Coast Guard, said one small boat which was carrying more passengers “overturned in the surf,” while the other managed to reach the shore.
He described the incident as a tragedy and said: “This is not necessarily people trying to find a better life. This is part of a transnational criminal organisation effort to smuggle people into the United States.
“These people are often labour trafficked and sex trafficked when they arrive.”
San Diego is close to the border between the US and Mexico and the US government has constructed a fence into the sea to the south of the city to deter migrants.
Eric Lavergne, a US Border Patrol official in San Diego, told Reuters this was one of a few hundred migrant smuggling events recorded in the area over the past five months – which is similar to the rate in recent years.