Speed may have caused an open-top army truck carrying 18 soldiers to flip over at Sydney's Holsworthy Barracks, leaving one person critical and 17 others seriously injured, police say.
Police say one man is on life support.
Soldiers in critical condition after truck rolls
Two soldiers are fighting for their lives and 15 others have been hurt after a military vehicle rolled on a dirt road at Holsworthy army barracks during a training exercise.
Police said crash investigators were looking into the cause of the crash, which happened on a dirt road during a training exercise about 8.40am today.
Inspector Steve Blair, from the Metropolitan Crash Unit, said early investigations suggested the Unimog multipurpose truck may have been speeding.
"It was on a back road and there was a bend involved, so for whatever reason the truck has left the road," Inspector Blair said.
There were two people in the front cabin of the truck and 16 soldiers in the back tray, he said.
Two people were reported earlier to have been critically injured, suffering head and spinal injuries, while others, including the truck driver, were left with serious injuries.
The remaining soldiers suffered a range of minor injuries, including cuts and scratches, and were treated at the field hospital in the barracks.
There were originally reports of up to 12, 15 and 17 soldiers involved, but that number was updated by authorities through the day.
A Defence spokeswoman said more information on the crash would be provided as soon as possible.