Yusuf Tifow, 16, was shot late Sunday evening. Toronto police were called to a building at 2240 Weston Rd., where they found him in a 19th floor apartment.
The teenager was rushed to hospital, where he was pronounced dead.
Tifow didn't live in the building where he was shot, but at a different apartment building on the other side of the Humber River.
On Tuesday, police said they had made an arrest in Tifow's death.
A 14-year-old boy faces a single charge of manslaughter. Because of his age, the accused cannot be publicly identified.
Police are crediting the public for coming forward to help with the investigation, which has led to charges being laid quickly.