A 17-year-old boy is in critical condition after police say an officer shot him with a stun gun during a traffic stop.

Sgt. Darrell Schmidli says the driver was stopped Sunday afternoon because of an outstanding warrant. He says the driver refused to roll down the window or get out of the car. He says the officer used the stun gun on the teen, who allegedly struggled with police as he was removed.

The teen was hospitalized in critical condition. Police say they don't know what caused the medical emergency.

A friend who witnessed the stop tells WDAF-TV the teen was using his cellphone to record the officer. Another witness tells the station she saw the teen convulsing.

Schmidli says police will review video of the stop.

Ethan Miller/Staff Getty Images News