A woman has been left with life-threatening injuries after being hit by a police car in Cairns on Thursday morning.Police said a police vehicle collided with the female pedestrian at the intersection of Sheridan and Lily Street at around 7am.Officers rendered immediate medical assistance and the 71-year-old woman was transported to Cairns hospital. Lily Street has been closed between Digger and Sheridan Streets and motorists have been urged to avoid the area.The Forensic Crash Unit is investigating.