Three men, aged 17, 22 and 27, were injured after a noxious substance was thrown over them in Dalston in the early hours of Sunday.
Their injuries are not life threatening however it is not known if they will be life changing, police said.
Two men appeared to target people walking away from Dalston Superstore on Kingsland High Road just after 5am, one witness said.
The man, who asked not to be named, told the Standard he woke to hear “a commotion” outside a friend’s flat close to the popular gay bar.
He described the moment a car stopped in the middle of the road and two men “jumped out and started beating people”.
The 26-year-old witness said: “They were punching at people walking either side of the road. One man was being kicked as he lay on the floor.
“The people were terrified, they weren’t fighting back.”
The men are then said to have taken water bottles from the car and began squirting passers-by with a “noxious substance”.
He added: “My first thought was ‘why are they squirting water’ but then I realised it was acid.