The collision between two cars in the Low Moor area left one female passenger with life-threatening injuries.
It happened on Common Road, near the Guide Post Hotel, when a silver Vauxhall Astra and a blue Honda Jazz collided shortly after 8.30pm.
A police spokesman said: "A 68-year-old female passenger in the Honda Jazz suffered life-threatening injuries as a result of the collision and is in hospital."
He said her condition had been described as critical.
Also in crime: Eight men jailed for three decades after Leeds United fan run over and killed in mob attackOfficers now want to speak to anyone who witnessed the crash or who saw either of the vehicles immediately beforehand.
Information can be passed to the Major Collision Enquiry Team via 101.