One man was killed and seven people were injured, two of them seriously, in a series of stabbings in the city of Birmingham in England, on Sunday (Sep 6), police said.

"We can now confirm that we have launched a murder investigation following last night's events," West Midlands Police said.

Police also said they were seeking a single suspect, adding that the victims of the attacks appeared to be randomly selected and did not target any one community or appear to be gang related.

Chief Superintendent Steve Graham said there was "no suggestion" at all that this was terror-related, and that it appeared to be a "random attack".

Britain's Foreign Secretary Dominic Raab said he had no information to indicate the incidents were terrorism related but the public should stay "very vigilant".

West Midlands Police were called to reports of a stabbing in Birmingham city centre at about 12.30am.

"A number of other stabbings were reported in the area shortly after," they said in a statement.

Police cordons were in place on Sunday morning in three separate locations in the city centre: Hurst Street, Irving Street and Edmund Street.

A knife was visible to a Reuters witness beside a drain in Edmund Street.

West Midlands Mayor Andy Street said the series of incidents in the Hurst Street area of the city centre appeared to be related but the motivation for them was not yet understood.

"At this early stage it would not be appropriate to speculate on the causes of the incident," the police said.

A witness told the BBC she saw "multiple people having fist fights".