"There were two ladies and two kids in the car, and one of the ladies was pregnant," the worker said.
She was not badly injured, he said, describing her as "okay" following the crash.
A local woman who was on her way to work at the Four Square said the front of the bus was "concaved" after the collision.
"There was broken glass everywhere, the car was wrecked and its tyres were all skewed."
The road was closed to allow emergency crews to operate safely and diversions were being put in place, police said.
St John Ambulance said it sent three vehicles to attend the crash and treated six patients, who were transported to a medical facility.
One person was in a moderate condition, while five others were in a minor condition, it said.