The feds will be investigating another Missouri town’s police after a stun-gun incident left a 17-year-old in critical condition. The FBI announced it would probe the Independence, Missouri, police on Monday. Witnesses say a police officer, identified by the department as Tim Runnels, acted excessively rough when he used a stun gun on Bryce Masters during a routine traffic stop. The officer reportedly grew frustrated that Masters’ broken window wouldn’t open for him. “Several times, the cop put his foot on the kid like he was stepping on his neck, but it was on his back,” said Robert Baker, a man who lives near where the incident took place. “I think [the officer] was wrong, because the kid tried to explain to him that his window won’t roll down.” The FBI is already investigating the police of Ferguson, Missouri, following the fatal shooting of unarmed black teenager Michael Brown.