HARTFORD, Conn. (AP) Hartford Mayor Pedro Segarra is pledging a thorough investigation of a police officer's use of a stun gun on a city teenager, whose family calls the use of force unnecessary.

Deputy Police Chief Brian Foley says the officer shot 18-year-old Luis Anglero with a stun gun Tuesday afternoon as police were breaking up an unruly crowd. Foley says Anglero was a ``clear aggressor and agitator.''

Surveillance video shows the officer shooting Anglero after the teen stopped advancing toward the officer and put his hands down. Relatives say the teen fell, hit his head and appeared to have a seizure.

Anglero is being treated at Hartford Hospital. Police charged him with interfering with police and breach of peace.

A police report identified the officer as Detective Shawn Ware, who didn't immediately return messages Thursday.