An elderly man is fighting for his life after he was critically injured attempting to stop his car from being stolen in Melbourne's northwest on Saturday night. Victorian Police said a manhunt was underway after the hit-and-run incident at Heidelberg West at about 7.30pm. Police are investigating a hit and run in Melbourne's northwest. Police said it had been reported to them that the man was struck on Blackwood Parade after attempting to stop his car being stolen by an unknown person. Advertisement AdvertisementAdvertisement AdvertisementThe vehicle did not stop when the man was injured and the car thief fled the scene, police said.