A security guard suffered "potentially life-changing injuries" when armed robbers tried to smash their way into a central London shop, police have said.
Officers said the attempted raid took place at Watches and Jewellery in New Bond Street at 11:05 GMT on Monday.
One of the gang sprayed people who got close to the group with a noxious liquid, injuring a guard.
However, the group left empty-handed after staff managed to operate the security shutters.
Six men were seen riding at a high speed from Oxford Street towards the store, officers said.
One moped was ridden on the pavement while two others mounted the pavement and caused pedestrians to scatter at a junction near the store, police said.
When staff closed the security shutters the gang fled on their vehicles, nearly knocking over a member of public.
The injured security guard, who it is believed was sprayed with ammonia, remains in hospital and is thought to have potentially life-changing injuries.
No property was stolen, but the damage to the store is estimated at several thousand pounds.
The store's manager Nino Santi had described the Met's response time as "scandalous" saying officers took about 30 minutes to respond.
But a Met Police spokeswoman said they were alerted at 11:09 GMT and armed response vehicles were assigned within three minutes.
She said officers were in the area at 11:23 GMT and, as it was an armed incident, made the locality safe and waited for armed colleagues before entering the shop at 11:34 GMT.