According to a school source, the incident occurred about 9.40am.
The source said Azim Hakimi Abu Shuja, 15, was believed to be trying to retrieve a friend’s schoolbag on the ledge outside the third-floor classroom when he lost his balance, causing him to slip and fall to the ground.
The body was taken to Putrajaya Hospital for a post-mortem.
Education Minister Mahdzir Khalid conveyed his condolences to the victim’s family through a posting on his official Facebook page.
The Federal Territory Education Department and the police were still investigating to determine the actual cause of the incident, the source said.