Three U.S. Army Soldiers were killed and three more injured in an accident involving the 25-ton armored Bradley Fighting Vehicle when it rolled into water, the military said in a statement.

The army provided no details on the nature of the accident, which is under investigation, except to say it occurred during an exercise at Fort Stewart.

“Six soldiers were involved, with three pronounced deceased on site, and three more evacuated to Winn Army Community Hospital where they are being treated and evaluated for their injuries,” a Fort Stewart Hunter Army Airfield statement said.

Fort Stewart is about 30 miles southwest of Savannah, Georgia.

“We are all devastated after a training accident this morning on the Fort Stewart Training Area,” said Major General Tony Aguto, commanding general of the 3rd Infantry. “We are extremely saddened by the loss of three Dogface Soldiers, and injuries to three more. Our hearts and prayers go out to all the families affected by this tragedy.”

The names of the soldiers killed in the accident will be released once their next of kin have been notified.

The Fort Stewart incident comes as more than a dozen American service members have been killed in training exercises in the past year. The death toll has prompted calls from military families and congressional leaders for improved training standards and practices.

As The Washington Post reported in August, fatalities in training exercises outnumber combat deaths 4 to 1. According to the Pentagon, training fatalities are down overall, but at least 15 service members have been killed in the past year. Those fatalities also represent an increase from last year.