A 32-year-old man is on life support after he was pepper-sprayed during a confrontation on a Toronto bus.

The man has been identified as Jasen Drnasin, who family members say was born in Split, Croatia, and was one of the first Croatians to graduate from West Point, the U.S. military academy in New York State.

At about 10 p.m. Sunday, special Toronto Transit Commission constables were called in after a disturbance was reported on a bus in the west-end area of Royal York Road and Eglinton Avenue West.

In an effort to subdue the man, the transit employees sprayed him with pepper foam. Transit officials also called in Toronto police.

The man broke free and began running down Eglinton Avenue, said Rose Bliss, a spokeswoman for the Special Investigations Unit which is probing the incident.

Police officers caught him and after a "fierce struggle" managed to handcuff him, Bliss said.

The man then had a seizure and was taken to hospital where he remains in critical condition, she said.

The SIU is a provincial agency that probes incidents of injury or death involving police. It has no jurisdiction to investigate the involvement of TTC constables.