Two helicopters crashed during training flights at the Ford Ord Army base, killing one soldier and injuring three others, the Army said.

Investigators were trying to determine Thursday if the two choppers, each with two soldiers on board, collided before they went down 150 yards apart Wednesday night, said Capt. Guy Shields, an Army spokesman.The soldiers' names were being witheld pending notification of relatives.

One injured solider was in stable condition at Silas B. Hayes Army Community Hospital at the base, about 100 miles south of San Francisco.