Toronto police detective Mike Perreault was driving home from work on Thursday, September 2, 2010, when saw a youth allegedly robbing a pedestrian at knife point. Perreault gave chase and made the arrest on a TTC bus. (Dave Thomas/QMI Agency)

TORONTO — Off-duty cop Mike Perreault had no problem finding his quarry during Thursday's rush hour.

The riders on the Wilson TTC bus pointed their fingers at the 17-year-old who moments earlier had allegedly mugged a man on Jane St. They even helped lead Perreault to the discarded knife on the floor of the bus.

The 12 Division detective was headed to a dry cleaner on Jane St. before going home and was in his vehicle waiting for a red light when he spotted a fight following a knifepoint mugging.

"It appears a male came into possession of another individual's wallet and other personal possessions while holding onto a knife," he said.

"Parked my car, got out and ... as it happened, ended up chasing after the fellow."

Perreault said he followed the suspect onto a bus and while trying to make the arrest, the bus driver called police.

While backup officers raced to the scene, Perreault was able to subdue the suspect.

"I ran onto the bus and all the citizens on board were very helpful and were kind enough to keep still and allow custody to take place," he said.

The passengers were "extremely helpful" by pointing out the suspect and where the weapon was dumped, Perreault said.

There were no injuries in either the mugging or the arrest, police said.