Police said they were called to the area of Jane Street and Wilson Avenue around 11:39 p.m. on Tuesday.
Officers said two people walked into a hospital with gunshot wounds shortly after the incident with non-life-threatening injuries. No victims were located at the scene.
Global News obtained video that appeared to show the moment shots rang out at the memorial.
People can be seen gathered when several gunshots are heard, sending bystanders running for cover. Throughout the course of the video, several people appear to return fire from behind a dumpster.
"I was kind of incredulous upon seeing the video," Supt. Steve Watts said.
"Anyone driving westbound on the 401 at that time could have easily been struck. There could have been extensive personal injury accidents caused by rounds hitting vehicles."
Watts said it's believed the initial shots came from a vehicle that quickly drove by and any return fire was indiscriminate.
Sources told Global News around 60 shell casings were recovered at the scene. Watts said it's believed more than seven guns were present at the time.
Watts said two people have since been arrested in connection with the shooting.
READ MORE: Toronto rapper Houdini shot dead at 21
"Both of these individuals have a history of firearms and violent offences in their records," he added.
"So they were currently on charges and now are facing additional charges of discharge firearm- and other related offences."
Their names weren't released.
Watts said it's believed the shooting is tied to some kind of gang rivalry. Police said Houdini, whose real name was Dimarjio Antonio Jenkins, may have had ties to gangs in the Driftwood community.
He was fatally shot in a brazen daylight shooting on May 26 in Toronto’s Entertainment District, just outside a hotel on Blue Jays Way near King Street West. He was pronounced dead on scene and two others were also injured, including an innocent bystander.
-- With files from Catherine McDonald, Tracy Tong and Gabby Rodrigues