FORT BLISS, Texas (AP) _ An Air National Guard pilot was killed in a jet crash today on a military reservation in southern New Mexico, the Air Force said.

Ground troops saw the twin-engine A-10 Thunderbolt II jet disappear behind a hill during a joint Army-Air Force training mission at about 9 a.m.

``Then they heard the explosion and saw a big mushroom cloud come up,'' said Capt. Tom Collins of Fort Bliss.

The aircraft is from the Air National Guard's 110th Fighter Group at Battle Creek, Mich. The name of the pilot was being withheld while relatives were notified, Collins said. No one on the ground was injured.

Air Force investigators quickly sealed off the crash site on the Fort Bliss military reservation, which stretches over hundreds of miles of desert in southern New Mexico and northern Texas.

Today's crash marks the fourth time in nine days that a military plane went down in New Mexico.

An aircraft carrier battle group commander and a pilot with 4,000 hours of flying time died Wednesday when their Navy FA-18, based in California, plowed into a ridge in northern New Mexico during a snowstorm.

An Air National Guard F-16B fighter aircraft from Tucson, Ariz., crashed Monday near the Arizona-New Mexico border, but both of its occupants ejected without injury.

An F-117A stealth fighter from Holloman Air Force Base, N.M., crashed in the Zuni Mountains on May 10, killing the pilot.