A woman managed to escape from three men who tried to steal her car during a bungled carjacking by driving away when the vehicle ran over one of the men's legs, police say.


The woman was stopped at traffic lights at the intersection of Macquarie and Pirie streets in Liverpool when a man approached the 45-year-old woman's car window about 1.30pm on Tuesday.


Police said the man threatened the driver with a knife and told her to get out of her Honda Civic, which initially she refused to do.


Two other men then approached the vehicle and opened the rear doors, at which point the woman ran out of the vehicle and began screaming for help from onlookers.


The woman's vehicle then rolled forward and ran over the leg of one of the offenders, who fell to the ground.


While the carjackers were attempting to help their friend, the woman jumped back into her car and drove away.


She called police, who searched the area but could not find the three men.


The first man is described as being aged in his 30s, with a medium build, olive skin and short black hair. At the time he was wearing a plain T-shirt and knee-length shorts.


The woman was unable to provide a description of the other two offenders.


Police said there were many pedestrians and vehicles in the area at the time, and appealed for anyone who saw the incident to call Liverpool detectives or Crime Stoppers on 1800 333 000.