(CNN) A Georgia homeowner shot and killed three teens as they approached his residence with their faces covered, authorities said.

The masked teens -- a 15-year-old and two 16-year-olds -- approached three residents around 4 a.m. Monday at the front yard of a home just outside Conyers and tried to rob them, the Rockdale County Sheriff's Office said.

One of the would-be robbers took out a gun and fired shots at them before one of the residents returned fire, authorities said.

"The victims of the attempted robbery were all uninjured, but the three attempted robbery suspects were all shot during the exchange of gunfire and succumbed to their injuries, one on scene and two at a local hospital after being transported," the sheriff's department said in a news release.

One neighbor heard someone asking for help, he told CNN affiliate WSB