“A number of other stabbings” were reported in the area shortly after and “this has been declared a major incident”, the statement added.

“We are aware of a number of injured people, but at the moment we are not in a position to say how many or how serious.

“However, all emergency services are working together at the scene, and making sure that those who are injured receive medical care.”

Footage aired on British television news channels showed large areas of the city centre cordoned off as police officers wearing forensic suits worked at the scene.

“Work is still going on to establish what has happened, and could take some time before we are in a position to confirm anything,” West Midlands Police said.

“At this early stage it would not be appropriate to speculate on the causes of the incident.”