Police cordoned off part of Wolverhampton city centre after the man, aged in his 20s, was found this afternoon.
Emergency Services have attended the scene in Dudley Street at Card Factory.
Police reported that the man harmed himself with a knife – and suffered serious injuries.
West Midlands Police, West Midlands Ambulance Service, and Midlands Air Ambulance have all attended.
A West Midlands Ambulance Service spokesman said crews were called at 3.05pm by the police.
A spokesman for West Midlands Police said: "Police were called to reports of a man harming himself with a knife in a shop in Dudley Street, Wolverhampton, just after 3pm on August 23. The man, aged in his 20s, is currently conscious and is being taken to hospital for treatment."
Our reporter Harriet Evans is at the scene
Dozens of stunned shoppers stood behind police tape at the scene on Dudley Street this afternoon as the incident unfolded.
The busy street was closed in places as more and more emergency service vehicles rushed to Card Factory.
An air ambulance was also seen circling above the city centre.
Police encouraged bystanders to keep moving away from the front of the Card Factory.