"It's almost inconceivable that these things can happen," he said.
The mayor said he believes Sunday night's shooting is "evidence of a gun problem" in Toronto, CBC reported.
"Guns are too readily available to too many people," Tory told reporters during a news conference two hours after the shooting took place.
Last week, Toronto police implemented the enforcement component of its "gun violence reduction plan." That includes some 200 additional officers on shift in particular neighbourhoods between the hours of 7pm and 3am — when most shootings occur.
Earlier, CP24 reported: "A large swath of the area has been blocked off as emergency crews respond to the scene."
Unconfirmed reports said a number of people had died.
Local reporter Jeremy Chohn tweeted: "Victims are spread across many blocks".
A witness who was standing near the scene told CTV that he heard about 20 shots and the sound of the weapon being reloaded repeatedly.
"And then, I saw the carnage as I ran down the street here to kind of follow the gunfire," the man told the station, who described the scene as "pretty crazy."
"I saw at least four people shot," he said.
Jody Steinhauer told CBC News she was at Christina's restaurant on the Danforth with her family when she heard what sounded like 10 to 15 blasts of firecrackers.
She said she was told to run to the back of the restaurant.
"We started to hear people scream out front," Steinhauer said.
Steinhauer said she was told that four to six people were shot.
Witnesses told CityNews that they heard up to 25 gunshots. One resident has uploaded a video to Twitter in which shots can be heard ringing out.
"Holy sh*t! The shooting on the danforth happened right in front of my place," she wrote.
"I was watching a movie and all I heard were gun shots … so scary.
"I don't feel safe in Toronto anymore, not even in my own neighbourhood."
Police were called to reports of shots being fired near Brass Taps Pizza Pub in Greektown, BNO reported.
"I heard shots followed by sirens a couple of minutes later near Chester station," Zaid Zawaideh said.
Canadian Broadcasting Corporation spoke to Andrew Van Eek, who lives in the area, about the shooting which Toronto police have now labelled a mass causality event.
Van Eek says he stuck his head out the window after he heard the gunshots ring out.
"There was a lot of commotion in the street," he said. "I saw somebody come just down the sidewalk and shoot into Demitri's restaurant."
He described the suspect as a white male, in his late to early 30s, who was dressed in all black. Police have yet to provide a suspect description.
"It was terrifying," Van Eek said.
