A second man has been charged after an Alberta Mountie's leg was broken when he was hit by an ATV in a troubled aboriginal community south of Edmonton.

RCMP say the constable was responding Sunday to reports of shots being fired at a home on the Louis Bull reserve townsite near Hobbema.

Police say the officer had stepped out of his squad car to stop a man driving an all-terrain vehicle and allege the driver accelerated and struck him.

On Wednesday, a 21-year-old man turned himself in at the Hobbema detachment, and was to make a court appearance Thursday.

The man and his 29-year-old brother are both charged with discharging a firearm with intent to endanger life.

The elder brother faces an additional charge of criminally negligent operation of a motor vehicle causing bodily harm.