Police have closed part of Bloomsbury Square with the junction of Bloomsbury Place in Central London following what is understood to be an attack involving acid.
Police paramedics and firefighters from the LFB were all scrambled to the incident on Tuesday at around 11.40am.
Anti Terror Police were also seen at the incident that remains an active investigation.
A large cordon has been put in place outside number 27 that is listed as a hotel and services flats.
Paramedics treated a white male in the back of the ambulance it is unclear if the man has been taken to hospital or his condition.
Police say they are currently dealing with an incident and a crime scene has been put in place
The Met Police have been approached for comment.