(CNN) -- Two helicopter pilots survived a crash in a field just minutes after takeoff early Tuesday morning in Mesa, Arizona.
The two pilots aboard the Boeing Bell 212 helicopter were able to walk away from the aircraft and were airlifted to area hospitals to be treated for injuries. Their names have not been released.
It is unclear why the chopper went down. Federal Aviation Administration officials and members of the National Transportation Safety Board are investigating the accident.
The helicopter was part of a three-plane Apache test flight for Boeing, CNN affiliate KPHO reported. The support helicopter was tailing an Apache Longbow when it left Falcon Field Airport, KPHO said. The helicopter crashed just four miles north of the airport at about 6:30 a.m. Tuesday.
Boeing used one of its own helicopters to transport paramedics to the scene.