Police have one man in custody after responding to reports just before 7 p.m. ET. of a person with a gun on a rooftop on Spadina Avenue, north of Dundas.
The area wasn't evacuated, but police asked members of the public to avoid the area for several hours and officers blocked off a section of Spadina Avenue, between Baldwin and Nassau streets, until around 10:30 p.m. ET.
Witnesses reported seeing about six police cruisers and dozens of officers in the area, including a few police officers on nearby rooftops.
CBC reporters on the scene say as many as seven people were brought out of a building in handcuffs by police and all appeared to be in their 20s or 30s.
Police made one arrest and on Wednesday told CBC News they do not expect to lay charges in connection with the incident, which is believed to have occurred at 388 Spadina Ave.
The arrested person's name has not been released.
Witness Krista Hessey described the scene as chaotic.
"Basically I saw a few scrambling police officers, them taping up the roads, emptying out the streetcars, and basically locking down and securing the area," she said.
"There was a lot of confusion from pedestrians. A lot of people were wondering what was going on."
Sara Taylor, who lives nearby, said it's hard not to get nervous when such an incident occurs so close to home.
"[I'm] totally afraid," she said. "I mean, it's confusing."
Resident Stephane Monette said he went outside to investigate the commotion, but a police officer ordered him back inside.