Authorities were searching for survivors after a small plane crashed off the coast of Half Moon Bay Sunday night.

Just after 7 p.m., customers at a restaurant at the Half Moon Bay Airport reported seeing a plane flying erratically before it went out of sight.

Crews with the San Mateo County Sheriff’s Office and the U.S. Coast Guard were at Moss Beach to search for survivors or any plane wreckage.

The sheriff’s office said before 11 p.m. Sunday that they located a plane in the water.

It’s not known at this time how many people were on board. Authorities said the visibility in the area Sunday night was poor.

The plane is believed to have taken off from the East Bay.

Further information wasn’t immediately available.