People partying at the Notting Hill Carnival had a "mildly acidic liquid" thrown at them on Sunday night (August 27), police have said.
The liquid was hurled at people gathered in St Charles Square, Ladbroke Grove and caused a panic in which two people were injured and had to be treated by paramedics at the scene.
Three people reported having skin irritation after the incident, but it was described as "not serious" according to Metropolitan Police .
On the second day of the festival there was another unrelated acid attack scare, with people seen running away from the scene however no liquid was thrown.
Police are investigating the cause of the panic.
Before the bank holiday carnival took place, Dave Musker, who is in charge of policing the event, said: "People should be under no illusion that if they think they can swan in with a bottle of Lucozade with acid in and not be able to be detected by police.
"We have the methods, the people, the highly-trained professionals, and we will look at them, and I will press for them to be arrested and charged and brought before the courts."
The scare follows a summer of high profile acid attacks in London.
Police have not yet made any arrests in connection to the incident and are appealing for information.
Any witnesses, or anyone with any information, can contact police via 101, or via Twitter @MetCC.
To give information anonymously call Crimestoppers on 0800 555 111.
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