LONDON (AP) — A U.S. Air Force fighter plane with one pilot on board crashed into the North Sea on Monday. The status of the pilot wasn’t known.

The F-15C Eagle from the 48th Fighter Wing was on a routine training mission from RAF Lakenheath when it crashed at 9:40 a.m. local time (4:40 a.m. EDT). The cause of the crash wasn’t immediately clear.

U.K. search and rescue authorities are taking part in the search of the crash site.

Lakenheath is a Royal Air Force base that hosts the U.S. Air Force’s 48th Fighter Wing, known as the Liberty Wing. The base is about 80 miles (130 kilometers) northeast of London.

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