The province's police watchdog has launched an investigation after a traffic stop uptown ended in one arrest and one suspect on the lam who is believed to be armed with a gun.

According to the Special Investigations Unit, officers attempted to pull over a vehicle travelling westbound on Eglinton Avenue East around 12:30 p.m. Thursday. The vehicle drove away and a short time later hit a light standard near Rumsey Road.

One passenger, a woman in her 60s, was taken to hospital with a back injury, and another passenger was arrested.

The driver of the vehicle fled the scene.

While Toronto police cannot comment on the investigation now that the SIU has taken over, police tweeted that they are searching for a person with a gun and have closed Eglinton between Hanna Road and Sutherland Drive, as well as Rumsey from Eglinton.

The SIU is asking anyone with information to contact the lead investigator at 800-787-8529. Video evidence related to the incident can also be uploaded to the SIU's website.