SAN DIEGO (CBS 8/ CNS) - Two firefighters were injured Tuesday when a fire engine crashed during a training exercise in an Otay Mesa field, authorities reported.

The brush engine from Station 29 rolled over twice before finally stopping on its side. The fire truck slipped of a dirt road on Otay Mountain during a training exercise Tuesday morning. 

Fire officials said the crew inside walked the road first to make sure it was safe, but once they started to drive on it, they quickly realized they were in trouble. 

"Didn't feel quite so right, so they started to back out and when they backed out, the front tire slipped off the road, and the engine rolled twice down the hillside injuring two fire fighters who were transported to the hospital," said Lee Swanson, San Diego Fire spokesman. 

The two injured firefighters were conscious after the accident. They got out the rig on their own, and their injuries were moderate to minor. 

The two firefighters are assigned to San Diego Fire Station 29 on West San Ysidro Boulevard.

Engine Company 29 is based out of the San Ysidro area, and it took help from a tow truck and bulldozer to get it out.

CHP and San Diego Fire are investigating.