Toronto police say they are executing a search warrant inside a Regent Park highrise where a teenage boy was found suffering from multiple gunshot wounds in a stairwell two days ago.

Homicide investigators are probing the fatal shooting of 15-year-old Tyson Bailey, a high-school student who did not have a criminal record.

On Friday afternoon, Bailey was found inside the 13th floor stairwell at 605 Whiteside Place, a highrise building operated by Toronto Community Housing.

Police say he was bleeding and surrounded by shell casings. They believe the shooting was targeted.

The teenager was rushed to St. Michael's Hospital, where he later died.

On Sunday afternoon, the homicide squad tweeted that its officers were executing a search warrant "on the 13th floor of [the] Whiteside Place crime scene."

In 2010, two other teenagers were shot dead when exiting an elevator at the same Whiteside Place building. They had just left a party at the building when they were killed.