Guam ? A B-2 stealth bomber crashed at an air base on Guam but both pilots ejected safely and were in good condition, the Air Force said.

Thick black smoke could be seen billowing from the wreckage at Andersen Air Force Base, said Geanne Ward, a resident in the northern village of Yigo who was on the base visiting her husband.

Ward said she didn’t witness the crash but noticed a rising plume of smoke behind the base’s air control tower.

A board of officers will investigate the accident.

Each B-2 bomber costs about $1.2 billion to build. All 21 stealth bombers are based at Whiteman Air Force Base in Missouri but the Air Force has been rotating several of them through Guam since 2004, along with B-1 and B-52 bombers.

The rotations are designed to boost the U.S. security presence in the Asia-Pacific region while other U.S. forces diverted to fight in the Middle East.