According to the police, the incident took place around 4pm on Tuesday at Yan Tin House, Hing Tin Estate.

The video footage showed that the boy in diaper was hanging by the window of the flat, and the mother had already come and grabbed her boy.

It took more than a minute before the mother successfully retrieved the boy, who also tried to climbed the wall with his legs, back into the flat safe and sound.

According to the grandparents of the boy surnamed Wong, he climbed towards the window from a bed and slid his body through the window grilles. Luckily he didn't immediately fell down -- his body was trapped in between a rack for hanging clothes.

The baby boy aged around two then started screaming as he didn't know how to talk yet, alarming his mother to come to the rescue.

The grandparents added that the boy was sent to United Christian Hospital.

They also said they will have workers to come to their home as soon as tomorrow to seal the window grilles which left holes for the small kid to get through.

The incident was reported to police by the security guard of the building. Officers arrived and found the crisis has been averted. The baby boy was unharmed.

No one was arrested in the incident.