Passers-by became involved when robbers who targeted a jeweller's store were making their getaway.
A 66-year-old man tried to knock them off their motorbikes with a billboard, while other people took pictures of the raiders as they fled.
The drama happened yesterday afternoon at a jeweller's in Newport Street, Bolton, Greater Manchester.
Police said four offenders travelling on two stolen motorbikes parked outside the shop. One, armed with an axe, waited outside with the bikes while the other three went inside. They were also armed with axes and crowbars.
The trio threatened staff before smashing glass cabinets and stealing a large amount of jewellery, then ran out and made off on the motorbikes.
A man who witnessed the robbery tried to knock them off the bikes with a billboard. He was hit by one of the bikes and taken to hospital for treatment to minor injuries, but has since been discharged.
Detective Sergeant Iqbal Ahmed said: "These robbers have brazenly committed this robbery in broad daylight on a pedestrianised street, stealing a large amount of jewellery from the store.
"Passers-by on Newport Street had no doubt as to what these offenders were up to and were obviously infuriated by what they could see unfolding before their eyes.
"One man courageously tried to stop the robbers as they made off, while a number of other members of the public took photos on their phones, which they sent to police and which we are now issuing in an appeal to identify these individuals.
"I would like to thank all of these people for their bravery and for taking a stand against these criminals, however, I would also urge people to be conscious of their safety in incidents such as this and to not unnecessarily put themselves in danger. Thankfully the man knocked over by the bike was not seriously injured.
"These two bikes were stolen for the specific purpose of being used in this crime – I am appealing for anyone who may have seen the bikes either shortly before or after the robbery, or who may know where they are being kept now, to please get in touch."
The four offenders were wearing dark, waterproof clothing, and one had yellow reflective hi-visibility trousers. They were all wearing motorbike helmets.
One of the bikes involved was a Suzuki Enduro. The two bikes were stolen from separate addresses in Bolton earlier in the day.
Anyone with information is asked to call Scholey Street police station on 0161 856 5594 or contact Crimestoppers anonymously on 0800 555111.