One man has died after being shot by a Toronto police officer on Halloween night, the Special Investigations Unit says.

The incident occurred in Riverdale Park, in the city's east end, at about 9:30 p.m.

The SIU, Ontario's police watchdog, says two uniformed officers stumbled upon what appeared to be a mugging in progress.

When police moved in to arrest the two suspects, there was an altercation, and one officer fired his weapon, hitting one man, the SIU says.

The unidentified 18-year-old suspect was taken to St. Michael's Hospital, but he later died from his injuries. The SIU has not said where he was hit.

The second young man involved was arrested at the scene and taken into custody.

The SIU-- a civilian agency that probes all incidents involving police which result in death or serious injury -- says no other information is available at this time.

The park remained closed to the public on Thursday while investigators scoured the scene for evidence.

There was a second shooting on Wednesday night, in the city's west end.

Just before midnight, a gunman walked into a restaurant at Bloor and Ossington Streets and fired several times, hitting a 23-year-old man in the stomach.

A witness said the victim had answered a knock at the back door moments before being shot by the gunman.

The victim was taken to St. Michael's Hospital in serious condition.

No arrests have been made in the second incident and police have not yet released a motive.

With a report from CTV's Jim Junkin and files from The Canadian Press