Two males were rushed to hospital on Sunday morning after being found, both without vital signs, in a beach area near Victoria Park Avenue and Queen Street East.
Both would be pronounced dead within hours.
Police say one brother was visiting from out of town.They spent the night at the beach.
Foul play is not suspected in their deaths.
The family has requested that police not identify the brothers publicly.
Passersby spotted man on beach
Earlier Sunday, Toronto EMS Supt. Martin Johnston told CBC News that two people were out with their dogs when they spotted one of the men lying on the beach in cardiac arrest.
"One of these two passersby was a nurse from Sick Kids, she initiated CPR and called 911," said Johnston.
Paramedics and police responded to the scene after the 911 call came in just before 9 a.m.
Johnston said a second patient was pulled out of the water by the Toronto police marine unit.
While the men were found on a part of the beach located just east of a water-treatment plant, Johnston said they were transported to another stretch of beach to the west where they could be put in ambulances and taken to hospital.
"One patient had a pulse during transport and the other was still in cardiac arrest," said Johnston.