Car crashes into Melbourne excavation pit

A woman has been critically injured after a car she was in plunged almost 17 metres into an excavation pit in Melbourne.

A car with three women inside lost control on a roundabout in Flemington crashing through temporary fencing at a construction site before dropping into the pit just before 2.30am AEDT on Thursday.

The front seat passenger is in the Royal Melbourne Hospital with abdominal and lower body injuries, including a suspected broken pelvis, after being trapped in the car for more than 1.5 hours.

The driver and back seat passenger were also admitted to hospital but weren't as badly hurt.

MFB commander Rick Gili told radio station 3AW it was incredible that anyone survived the crash.

"When we arrived we found the car at the bottom of the excavated area where the building was going to go," he said.

"The car was upside down, it landed on its roof.

"We saw where the car had gone through and two occupants were able to get out of the vehicle unassisted."

Commander Gili said the woman with abdominal injuries had to be winched from the wreck.

"It was quite a tricky manoeuvre, because there's a lot of reinforcement and steel coming out from the side of the walls, so we had to make sure as we hauled her up she didn't get tangled up in all the steelwork," he said.

"(I'm) Absolutely amazed how anybody survived the fall, it's incredible."

Mr Gili said he had called in Worksafe to check whether the wall fencing off the pit was sufficient.