A boy was found at the bottom of a slide at Inflatable World Toowoomba with injuries to the back of his head. Credit:Instagram/Inflatable World

Police have appealed for anyone who may have witnessed the boy playing at the centre on Sunday to contact them.

Workplace Health and Safety is also investigating.

Inflatable World Toowoomba said in a post to their Facebook page on Monday: "We are devastated by the news that a child has passed away in hospital after collapsing at our venue on Sunday afternoon.

"Inflatable World notified Worksafe on Sunday and they began investigating.