Toronto EMS said they have transported three people, a man and a woman in their 20s and a man in his 40s, to a trauma centre. EMS said they were called at 7:56 a.m. to Carlton and Church Sts. All three stabbings were in the torso area.
Toronto Police have confirmed they have one suspect in custody.
The Ryerson athletic centre opens at 9 am on Sundays. Police have cordoned off the doors to the former Maple Leaf Gardens.
Toronto Police tweeted they had closed down the street for a police investigation.