Updated with names of crew.

The Air Force announced that a C-17 Globemaster III crashed shortly after takeoff from Elmendorf AFB, Alaska, on Wednesday, killing the four crewmembers.  There are indications the crew was practicing for the upcoming Arctic Thunder airshow this weekend.  While large aircraft occasionally have incidents on landing or on the ground, the catastrophic loss of a military cargo aircraft from a flight mishap is a relatively rare event.

Elmendorf leaders have announced the 2010 Arctic Thunder airshow will proceed as planned.

As is the common practice, the Air Force did not speculate and will conduct a month-long investigation to determine the cause.

UPDATE: The Air Force released the names of those killed on the C-17:

Maj. Michael Freyholtz
Maj. Aaron Malone
Capt. Jeffrey Hill
Master Sgt. Thomas Cicardo