Teammates of a teenage boy who fell to his death inside Sydney's Queen Victoria Building are "absolutely devastated" by the tragedy and will wear black armbands in their next rugby match as a mark of respect.

Archie Hunt, 13, was visiting the CBD shopping centre with his family about 3pm on Sunday when he fell up to 30 metres to the ground inside the northern stairwell of the building, which was packed with shoppers at the time.

Archie Hunt, 13, fell to his death inside the Queen Victoria Building.

Archie, who attended Farrer Memorial Agricultural High School in Tamworth, was believed to be playing on a stair railing, possibly trying to slide down it, when he lost his balance and tumbled over the edge.

He suffered critical head and chest injuries, and died that afternoon in the Sydney Children's Hospital in Randwick.