The U.S. Coast Guard's San Diego air station launched a search-and-rescue helicopter Wednesday morning after receiving a report of a "downed aircraft" off San Clemente Island, officials said.
Three people were said to be onboard the missing aircraft, the Coast Guard said on Twitter shortly before 9 a.m.
The aircraft was reported to have gone down about 1 mile southwest of the island, located about 70 miles west of San Diego.
A Coast Guard MH-60 Jayhawk helicopter was en route to the area.
DEVELOPING: More details will be added to this report as they become available.