Police said several people were gathered outside a townhouse at 5:50 p.m. Thursday when another group approached and began firing.
Five of the people milling about were shot, they said. Three men were sent to hospital — one with life-threatening wounds.
About 25 minutes later, officers investigating a car several kilometres away had an interaction with the occupants of the vehicle, during which police shot one man, the province's police watchdog said in a statement.
The man suffered non-life threatening injuries, the Special Investigations Unit said.
Glenn Howell, who lives near where that incident happened, was sitting at his dinner table with his family eating "awesome homemade hamburgers," when he saw the commotion.
"I'm facing the window and we notice this car driving up my driveway at a fast speed," Howell told The Canadian Press.
The black car hit Howell's car and drove it into his carport, he said.
Then he heard a huge bang and saw a bunch of people running around his front yard with guns.
He yelled at his wife, son, mother and sister — all over for dinner — to get down as he peered around a wall to watch the events unfold.
He finally saw a man with a vest with the word "police" on it.
"He looked at me and made a phone gesture with his hand and so I called 911," Howell said.
He saw one officer pin and handcuff one man in his front yard and other officers bolt through his and his neighbours' backyard.
Three Toronto men — Akeem Bailey, 25, Clifton Vassel Youria, 29, and Maurice Smith, 21 — and twenty-year-old Daniel Duarte-Alvarez, of Mississauga, face a total of 112 charges.
They are scheduled to appear in court Friday.