A US F-15 fighter jet crashed in the North Sea off England Monday and the condition of its pilot is unknown, CNN reported referring to a statement from the 48th Fighter Wing.

"A U.S. Air Force F-15C Eagle crashed at approximately 0940 [local time] today in the North Sea. The aircraft was from the 48th Fighter Wing, RAF Lakenheath, United Kingdom," the statement said.

"At the time of the accident, the aircraft was on a routine training mission with one pilot on board."