Investigators were trying to determine what caused the death and injuries Monday night at the National Training Center at Fort Irwin, a remote facility 37 miles (60 kilometers) northeast of Barstow in the High Mojave Desert midway between San Bernardino and Las Vegas.
A military helicopter flew the three injured soldiers to a hospital in Loma Linda, where they were in stable condition Tuesday. The names of all four are being withheld until 24 hours after their families are notified.
The troops were doing an armored brigade combat team exercise, which emulates an overseas deployment to a war zone, Drylie said. Also participating in the training are National Guard members from California, Missouri, and members of the Air Force. He declined to comment further, saying the accident is under investigation.
Lt Col Christian Patterson, spokesman of the Mississippi National Guard, said the exercise has been suspended for the unit that the four members belonged to but the rest of the Mississippi Guard troops will still participate. He said no further details would be released to avoid compromising the investigation.
"It's basically like a full deployment overseas except that it's in the California desert," Drylie said.