One man was shot and another was injured as violence broke out after a foam machine malfunctioned at a nightclub in north-west London, police said.
An investigation is underway after officers were called to reports of violence outside a party in Harlesden on Saturday night.
One man, aged 22, was found with a gunshot wound to the leg and another, also 22, was treated for head injuries.
Both were taken to a central London hospital and neither of them are in a life-threatening condition, Scotland Yard said.
Police said they were called to the scene, in Abbey Road, at around 3.10am last night.
A spokesman added: "At this early stage it is believed both men had attended a foam party at the club. Around the time of the incident, a number of people had run from the club into the street after a foam machine appeared to malfunction, emitting a chemical smell."
No other injuries were reported, and the incident is not currently being linked to any other in the area, according to Scotland Yard.
Anyone with information is asked to contact Trident officers on 0208 358 0051 or contact Crimestoppers, anonymously, on 0800 555 111.
