Shots were fired from a car near St Brendan's Primary School and the victim was hit a number of times.
The shooting happened shortly after 15:00 GMT.
Ch Insp Jon Burrows said: "There are no words to describe the foolhardiness and complete disregard for the safety of the children and parents who were in the area at the time."
BBC News NI's home affairs correspondent Vincent Kearney said the victim is a well-known criminal.
The man is receiving treatment for his injuries.
Police have appealed for witnesses to contact them.
A man has been shot outside a primary school in Craigavon, County Armagh, as children were leaving the grounds.