A MINIBUS full of children had a close call today after it was left teetering over the edge of a five-metre cliff in Freshwater, on Sydney's northern beaches.

About 3.20pm emergency services were called to Stewart House after the bus crashed through the charity's fence and came to a halt dangling over a ledge on the property.

It was unclear late Tuesday what caused the crash, however, 15 children aged seven to 12 were safely removed from the bus shortly after it came to a halt.

The 25-seater bus was being driven by a 52-year-old woman. The woman also got off the bus without injury.

Police said the bus was believed to have been attempting to enter the facility when it travelled down a grass verge and towards the cliff.

Freshwater resident Kylie Gill arrived home about 15 minutes after the incident happened.

She said the driver was still seated in the vehicle as rescues services were carefully working to transport her off the bus.

"It is quite a deep escarpment there, it would have been pretty bad had it gone over," Ms Gill said.

"I'm glad it all worked out well."

Stewart House is a place that allows children in need to receive medical and emotional support for a short-term stay.

Witnesses said four police cars, two Fire and Rescue NSW trucks ambulances could be seen heading towards the scene from Harbord Public School.

A helicopter was also seen hovering above.

As of Tuesday afternoon, police were still attempting to piece together the cause of the accident.