Witnesses say there were chaotic scenes after a cyclist was pinned under an Australia Post truck for about an hour in Sydney's inner west.
Emergency services found the cyclist trapped at the intersection of May Street and the Princes Highway in St Peters on Wednesday morning.
Several ambulance units worked for almost an hour to free the 26-year-old, who was taken to Royal Prince Alfred Hospital with life-threatening injuries.
"We heard a lot of screaming, which we assumed was just someone being silly," a local worker told AAP.
"It was quite chaotic."
She said she called triple zero after seeing passers-by running to a stationary Australia Post truck and throwing a bike out from underneath the vehicle.
"There were a lot of people running around trying to help," she said.
"But obviously when someone's stuck like that the only people who can help are the professionals."
With the accident happening during the morning's peak-hour traffic, the street came to a "standstill", she said.
The 59-year-old truck driver was not injured but has been taken to hospital to undergo mandatory blood and urine testing.
Police are still appealing for any witnesses, who haven't spoken to them already, to come forward.
Australia Post said in a statement it is assisting NSW Police with its investigation into the accident and is unable to provide further comment at this stage.
