Tiger Tiger club goers were reportedly given caustic soda instead of salt for tequila and suffered extreme burns after coming into contact with the substance.
Four out of the five involved were also treated at the scene and were later taken to hospital.
The Daily Mail has reported that emergency vehicles, including an air ambulance, were called to the scene at the Haymarket venue, near Piccadilly Circus, in central London on 7 December.
One insider told The Sun: "A group of four women and a man necked the tequilas and used salt and lemon to soften the taste, then began to retch.
Advert
Other club goers were reportedly horrified and thought they were subject to a potential terror attack.
The source added: "There was panic. People thought it was some kind of terrorist incident."
"It took a long time to establish what happened. Apparently, the club kept salt and caustic soda in similar containers and there had been an honest accident."
The Sun reports that clubbers were bleeding from the mouth, however, this is unconfirmed.
According to ChemicalSafetyFacts.org: "Sodium hydroxide (NaOH), also known as caustic soda or lye, is a highly versatile substance used in a variety of manufacturing processes. Sodium hydroxide is a co-product of chlorine production."
Advert
The Met police told LADbible: "Police were called at approximately 22:50hrs on Tuesday, 7 December following reports of four people who had suffered burns after coming into contact with a substance, believed to be a strong alkali, at a venue in Haymarket, W1.
"The four people – all female – received treatment at the scene before being taken to hospital; none of their conditions are life-threatening.
"A fifth, person – a male – also came into contact with the substance but has declined hospital treatment.
"The venue was closed as a precaution.
Advert
"The incident is not being treated as suspicious and there have been no arrests. The Health and Safety Executive has been informed."
A spokesperson for Westminster City Council told LADbible: "This is the subject of an ongoing investigation so we are unable to comment at this stage."
LADbible has contacted Tiger Tiger for comment.
Featured Image Credit: AlamyTopics: UK News