Los Angeles, California - Three people have died and nine are missing, including two children, after a boat overturned off the California coast, officials said Monday.

The US Coast Guard was alerted to a vessel in trouble near Del Mar, north of San Diego, around 6:30 AM (1330 GMT), spokesman Hunter Schnabel said.

A boat and a helicopter were dispatched to the spot, where four people were rescued and taken to the hospital.

"Three people were located and found to be deceased," he said.

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Interviews with survivors indicated that there are nine people still missing, two of whom are thought to be children, Schnabel said.

There was no immediate information on where the "panga-style" vessel had come from or where it was going.

However, "some individuals are suspected to be of Indian nationality," the spokesman added.

Pangas are skiffs with a high bow that are typically used for fishing, but have also been used by people coming across the sea border into the US from Mexico.

A fixed-wing aircraft was being mobilized in the search and rescue operation, which also included a Coast Guard cutter.