A 16-year-old Chatham boy is in custody after allegedly shooting his ex-girlfriend in the mouth with a BB gun.

Police say the accused confronted the 15-year-old victim when he saw her walking with friends last night.

They argued about their infant child.

The boy allegedly punched the girl in the back, then pulled out the BB gun and shot her in the mouth.

The victim was taken to the hospital for treatment.

The boy is charged with assault with a weapon.