One dead and seven injured after Birmingham stabbings
West Midlands police declared a major incident after officers were called to reports of a knife attack in the early hours of Sunday, with further stabbings then being reported.
The force said in a statement said: "We can now confirm that we've launched a murder investigation following the events in Birmingham city centre overnight.
"A man has tragically died. Another man and a woman have suffered serious injuries and five others have also been injured, although their injuries are not thought to be life-threatening.
"We believe the incidents, which took place between 12.30am and 2.20am, are linked and we're doing all we can to find whoever was responsible."
The force said it was at scenes across the city, including Livery Street, Irving Street and Hurst Street.
It urged witnesses or people who have CCTV or mobile phone footage to contact police.
Chief Superintendent Steve Graham, who is responsible for policing in Birmingham, said: "The events during the early hours of this morning are tragic, shocking and understandably frightening.
"Please be assured that we are doing absolutely everything we can to find whoever was responsible and try to understand what exactly happened.
"We have well-rehearsed plans for dealing with major incidents. Your safety is always our priority and that's why you'll see an increase in officers on the streets.
"In the meantime, we'd ask anyone who's in the city to remain vigilant and report anything suspicious to us."
The West Midlands Police and Crime Commissioner David Jamieson said: "Last night's events are truly terrible and have shocked the people of Birmingham, the West Midlands and the country.
"My first thoughts are with the victims and their families at this time.
"I have every faith in West Midlands Police, who are working extremely quickly on this investigation.
"My thanks also go to the ambulance and hospital staff who are working around the clock to help those who have been injured."