A police officer was threatened with a nail gun and a patrol car was damaged in Cromwell on Saturday.
Police say they were called to a house in the town early in the morning to investigate a complaint of intentional damage at a house.
When he arrived, the policeman was chased down the street by a man wielding a nail gun and had to hide while he called for backup from Alexandra.
Senior Sergeant Jill Woods says the man was on home detention at the time and had cut off his leg bracelet.
A police car was extensively damaged while help was on the way.
A 17-year-old was arrested a short time later. He is in hospital being treated for minor injuries after crashing his car while being chased by police.
Sgt Woods says it's too early to tell whether alcohol or drugs were involved in the incident.