Police are hunting a suspect after a commuter and railway ticket inspector had a substance thought to be acid thrown in their faces on a train in north London.
The male inspector and the female commuter were hospitalised after the incident on the London Overground, near South Tottenham station, at 8pm last night, but have since been released.
Passengers rushed to help the victims and used water to wash their faces.
A British Transport Police spokesman said Thursday that the victims had suffered irritation to their eyes, but had not been seriously hurt, and that a single suspect had been identified. The spokesman declined to provide further details about the person police are seeking over the crime.
The substance thrown on the victims was reported to be acid, but it has also been suggested that it may have been ammonia.
Police are continuing to work to determine what exactly the substance was.
In a statement BTP said: "British Transport Police, and Metropolitan Police colleagues, were called to an incident at around 8pm tonight at South Tottenham Station whereby a member of staff and a passenger had had a substance thrown over them whilst on a train.
"This has not resulted in any serious injuries although both parties were taken to hospital as a precautionary measure. Enquiries are continuing to trace the suspect."
Paramedics from the London Ambulance Service's Hazardous Area Response team arrived at the scene and took the victims to hospital, where they were treated, the Standard reported.
Rosie Busiakiewicz, whose sister was on the train at the time of the incident, tweeted about the incident saying: "Guy & girl had acid chucked on their face on @LDNOverground at South Tottenham - whole carriage (including my sis) pouring water over them!'
According to the Evening Standard, it is believed that the incident took place following a row over fares.
Mike Stubbs, director of London Overground, said: "This is a horrible attack on a revenue officer doing their job.
"We take every assault on staff and passengers extremely seriously and will be working closely with the police to assist them with their investigation and push for the toughest penalties."