Military.com has the details:
One of the pilots of the B-2 stealth bomber, Spirit of Kansas, reported a fire at takeoff from Andersen AFB, Guam which was followed quickly by loss of control of the bomber, according to a senior Air Combat Command official. The stealth bomber rolled uncontrollably to the right and fell between the taxiway and the ramp at 10:45 am Feb. 23 Guam time just after passing the control tower. It was attempting a takeoff toward the seaward end of the runway. The two pilots ejected with one being hospitalized. A dark plume of smoke rose from the crash site and civilians outside the base reported a second explosion about 30-min. after the initial impact.
These are some of the most modern aircraft in our inventory, and they’re over a decade old. So you have to admire the safety record here, though it’s worth noting that with only 20 aircraft in the B-2 fleet, crashes are going to be statistically less-likely. The Air Force has not signaled an intention to replace the downed B-2, as it has higher priorities these days. All of which makes this loss even more devastating–the B-2 is unmatched in its ability to quietly put iron on targets.

