A have-a-go hero appeared to chase two thieves fleeing a raid at a jewellery shop before throwing a wet floor sign at their getaway car.
In this video being circulated online, the man was filmed chasing after the raiders, who targeted Browns in Crossgates Shopping Centre on Monday morning.
Footage taken inside the precinct shows the pair, dressed in black, smashing a display window before making off with luxury watches and other jewellery.
Shocked shoppers watch as the two men use a hammer and axe to access the valuables while staff sheltered in a back room, shouting at onlookers to stay away.
As the pair flee with the haul, a man chases after them, picking up a 'wet floor'-type hazard sign from outside the shop doorway.
The suspects are seen jumping into their getaway car - a black Ford Fiesta which was waiting outside a pharmacy - and the have-a-go hero flings the missile at the retreating vehicle.
The car was later found abandoned behind the Britannia Hotel in Mill Green View.
Det Insp Richard Holmes, of Leeds District CID, said: "While no-one was injured, the staff involved have been left understandably shaken by this incident, which was also witnessed by a number of members of the public who were warned by the men to stay away.
"We are carrying out extensive enquiries to identify the men involved and would like to hear from anyone who witnessed the incident.
"The black Ford Fiesta they used had been waiting outside the Day-And-Night Pharmacy across the road and we want to speak to anyone who saw the men and the vehicle in the time leading up to the incident. We would also like to hear from anyone who saw the men abandoning the car behind the Britannia Hotel In Mill Green View."
Anyone with information is asked to contact Leeds District CID via 101 quoting log number 588 of May 15 or call the independent charity Crimestoppers anonymously on 0800 555 111.