Two men were taken to hospital tonight after the ‘noxious substance’ was thrown at them just before 7pm.
A video posted on Twitter shows one of them with his shirt off having water poured on him to try and help him and wash off the ‘acid’.
Paramedics and police officers surround him and there is a fire engine in the background.
‘I just gave them water, they were shouting and I gave them water and they were washing their faces.
‘They said: “We have got acid on us, we have got acid on us.”
Tower Hamlets Police said they were dealing with a ‘suspected acid attack’ however it was not immediately clear what the substance was, with some saying it could be bleach.
Police appealed for any information about the attack in Roman Road, Tower Hamlets, on the men who are in their late teens.
In a statement, the Met Police said: ‘Both have been taken to an east London hospital for treatment after an unknown liquid was thrown at them. Their injuries are not life threatening.
‘No arrests have been made. Enquiries are ongoing.
‘A crime scene remains in place.’
London Ambulance Service also attended the scene.
It follows a spate of acid attacks in the capital in recent weeks and months, with gangs said to be turning to it as a weapon.
The number of acid attacks rose by 65% last year to 431 – that is almost one every 20 hours.
Earlier this month, two men on a moped carried out five acid attacks during a spree across London which lasted less than 90 minutes, police said.