Woman, 81, dies after hit by Sydney bus

An elderly woman has died after being hit by a bus in Sydney's southwest.

The 81-year-old was struck at a bus terminal in Bankstown just after 10am on Monday.

She was treated by paramedics at the scene before being taken to Liverpool Hospital, where she died.

A crime scene has been set-up and the bus driver - a 64-year-old man - was taken to hospital for mandatory blood and urine tests.

The bus operator, Transdev, said it is working with investigators, a company spokesman told AAP.

Waris Rashid, who was serving a customer in a nearby shop when he saw the woman about to cross the road, was one of the first people on the scene.

"I heard the screams and looked over and she was under the bus," he told AAP.

"Me and a few others were trying to stop the bleeding."

Mr Rashid said he didn't have words to describe the "absolutely shocking" scene.