Dramatic footage showing moped-riding thieves fleeing after dousing a man with liquid near London's Harrods department store has been released by police.
In the headcam video bystanders can be seen rushing to the victim's aid with bottled water, apparently in fear that he had been attacked with acid.
Having witnessed the attack a passing black cab driver also offered to take the man to A&E, shouting: "I'll take you to the hospital, get in! Get him in!!"
The suspected attempted robbery took place in affluent Knightsbridge, west London, on Monday evening.
A Rolls-Royce can be seen gliding past as the pair of attackers, wearing dark clothing and black helmets, mount the pavement to make their escape.
The footage, apparently recovered from a passing motorcyclist, gives a compelling first-person view of the tense aftermath of the kind of attacks that have seen a worrying rise in recent months.
Figures from 39 forces in England and Wales showed a spike in the number of attacks involving corrosive substances, with more than 400 carried out in the six months up to April 2017.
Scotland Yard said it was called at 8.33pm on Monday to reports of an assault in Walton Place where "men on a moped" had thrown liquid in a pedestrian's face.
The victim, a 47-year-old man, was treated by paramedics at the scene before being taken to a central London hospital.
He suffered minor injuries and was subsequently discharged from hospital.
Scotland Yard said it is not known if the liquid was a corrosive substance, although enquiries are continuing to identify it.
The force said no arrests had been made at this stage as it released the footage in a bid to trace the pair.
To give information anonymously, witnesses to Monday's attack are urged to call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.