All eight crew members aboard the Air Force B-52 aircraft that crashed after takeoff Monday morning at Edwards Air Force Base, in California, are confirmed dead.

Officials confirmed the deaths at a press conference hours later. They described the victims as a mixed crew of uniformed military, government civilians and government contractors, according to local news station abc7.com. The names of the dead as of Tuesday morning had not been released.

The Air Force Base said early in the emergency response that the crash did not appear "survivable," and that it occurred during a "routine test mission."