One soldier was killed and another injured when two Bradley fighting vehicles rolled over at a checkpoint that had come under enemy fire in the northern city of Tikrit, U.S. Central Command said Sunday.

At least two Bradleys from the 4th Infantry Division had approached the checkpoint to help out during the firefight when they both rolled over Saturday, the military said in a statement. The incident was under investigation.

A Central Command spokeswoman had no further information on the fighting at the checkpoint.

The soldier's names were being withheld pending notification of next of kin.