A woman was trapped in her car several metres above the ground for more than an hour today after smashing through the brick wall of an office block in Sydney's west.

The woman, aged in her 60s, has told police she was leaving the level-one car park of an office block on George Street, Parramatta, when she lost control of her white Toyota Corolla and hit the building's brick wall about 11am.

The wall gave way, and her car was lodged halfway out of it with its bonnet touching the roof of an empty demountable classroom at Arthur Phillip High School, police said.

Rescuers could not get the woman out without stabilising the car first.

A NSW Fire Brigades spokesman said a crew worked for about an hour with a ladder truck before cutting out the back seat and pulling the woman through the boot just after midday.

She was taken to Westmead Hospital with minor injuries. An Ambulance NSW spokeswoman said she was "very shaken" but otherwise in good health.

A person who works in the building attached to the car park felt the crash.

"We are on level [three] and felt the building shake and saw lots of bricks, dust and smoke fall from the building under us," the person said.

The NSW Fire Brigades spokesman said the car was badly damaged but no school property was damaged. No one else was hurt.

Police said WorkCover would be notified and a structural engineer would be called in to examine the building.