Officers from 14 Division said they were called to the corner of Spadina Avenue and Nassau Street at about 6 a.m. for reports of shots fired, CTV News reported.
They arrived to find four people with gunshot wounds, including two reportedly with wounds to the head.
Toronto paramedics said two people were pronounced dead at the scene and another two were rushed to hospital trauma centers in life-threatening conditions.
The body of one victim was covered in an orange tarp on the west sidewalk of Spadina Avenue, north of Nassau Street.
No suspect information was immediately available, and detectives told CP24 they were still working to determine exactly what transpired.
HJ/PR