Ekalaka, Mont., residents said they heard a fire alarm go off around 9 a.m. Some saw parachutes leaving the plane while others saw smoke from the crash.
The two pilots and two weapons systems officers were on a routine mission from Ellsworth Air Force Base in South Dakota, one of the two U.S. bases that contain nation's whole fleet of B-1's.
"We are actively working to ensure the safety of the crew members and have sent first responders to secure the scene and work closely with local authorities at the crash site," 28th Bomb Wing commander Col. Kevin Kennedy said in a statement. "Right now all of our thoughts and prayers are with the crews and their families."
Ellsworth representatives said they would be conducting an investigation into the cause of the crash.
Picture from the crash site in Montana where the B 1 Bomber went down. pic.twitter.com/m5nhsSmJSc— KNBN-TV Rapid City (@NewsCenter1) August 19, 2013