LONDON - An American fighter jet crashed into the North Sea off the coast of England on Monday morning.

According to ABC News, an F-15C Eagle, from the U.S. Air Force's 48th Fighter Wing, was on a "routine training mission" with one pilot on board when it went down at approximately 4:30 a.m. ET, according to Col. Will Marshall, commander of the 48th Fighter Wing.

"The cause of the crash is unknown at this time," Marshall said in a video statement Monday. "Search and rescue efforts are currently underway, but the pilot of the aircraft is still missing. We will provide updates as they become available while prioritizing respect and consideration for the pilot's family."

The aircraft deployed earlier that morning from the U.K. Royal Air Force station near the village of Lakenheath in Suffolk, England. The base hosts U.S. Air Force units and personnel.

"We're extremely grateful for the timely response of our U.K. counterparts in support of these recovery efforts and remain hopeful that our Liberty Wing airman will be relocated and recovered," Marshall said.