A seven-year-old boy was critically ill in hospital on Tuesday after apparently being thrown from the roof of a six-storey shopping mall in Kowloon City.

The child's father, 58, is believed to have jumped to his death from the building after trying to murder his son, police said.

A security guard found the pair lying in a back alley on Monday night.

Chief Inspector Law Chin-hon said the father is thought to have had large gambling debts.

“Based on our initial investigation, the father used to be a transportation worker and is now a taxi driver. We will conduct an investigation into his financial conditions," Law said.