Another safety investigation has begun at Andersen Air Force Base, Guam, this time to determine why a B-1B Lancer bomber collided last week with two emergency vehicles on the base’s taxiway.

The bomber was stopped on the taxiway, and the aircrew had exited, when it rolled and hit two fire trucks, according to Andersen spokesman Capt. Joel Stark.

No one was injured, Stark said.

The aircraft, assigned to Ellsworth Air Force Base, S.D., was in transit from an air show in Singapore. It took off from Andersen around mid-day Friday, Stark said, but returned due to an in- flight emergency.

Stark said Monday he was still researching what that in-flight emergency was, but added “in-flight emergencies as precautions are not unusual.”

The bomber had landed safely and was on the taxiway when the collision occurred, Stark said.

The extent of damage to the aircraft has not been determined, he said.

The aircraft was not carrying munitions.

The jet is worth an estimated $283.1 million, according to a U.S. Air Force fact sheet.

A team from Andersen has begun an interim investigation into the collision, Stark said.

Meanwhile, the investigation into the crash of a B-2 stealth bomber upon take-off on Andersen’s runway on Feb. 23 continues, Stark said.

The bat-like stealth bomber, valued between $1.2 and $2 billion, was a total loss.

An Air Force safety board on the island looking into that incident has 30 days to investigate.

The “Spirit of Kansas” was one of four B-2s deployed to Guam from the 509th bomb Wing at Whiteman Air Force Base, Mo.