The United States Coast Guard responded to a reported aircraft crash off the coast of the Channel Islands Wednesday morning, and after rescuers found a debris field, they’ve begun searching for three missing people.

The debris field was found where the aircraft was believed have crashed about 1 mile southwest of San Clemente Island, the southernmost of the Channel Islands.

A MH-60 Jayhawk helicopter and its crew from U.S. Coast Guard Air Station San Diego are assisting with search and rescue efforts, the USCG said on Twitter.

The U.S. Navy and Customs and Border Protection are also involved.

The time of the crash, what may have led to it and the conditions of those aboard are not yet known.

Check back for updates to this developing story.