Several people were stabbed in Birmingham city center and the police declared a “serious accident”.
West Midlands police said they were called in to report a stabbing around 00:30 BST on Sunday, with further stabbings reported shortly thereafter.
Police said there were “a certain number of injuries” but could not say how many or how serious they were.
West Midlands Mayor Andy Street said the incidents in the Hurst Street area “appear to be related.”
However, he said the motivation is still unknown. A police briefing is expected shortly.
The BBC’s Nick Clitheroe, at the scene, said the incidents took place in a part of Birmingham where the Gay Village meets Chinatown, which is often full of clubs and bars at night.
He added: “This seems to have started as a big fight between large groups of people, but obviously at some point knives were drawn and stabbings occurred.
This will be of great concern to all the people who live here. “
A “serious accident” describes any situation that involves serious harm or a risk to the safety of the public.
It also means that there are special arrangements for the cooperation of all emergency services.
Witness Cara Curran, a club promoter who works at the Arcadian Center, said she had been busier overnight than ever since the lockdown.
She said she had finished her shift around 00:30 BST and was drinking with her colleagues when she heard a “loud roar and a lot of hustle and bustle.”
He added: “I found more people arguing … people from pubs and clubs came out and started to see what was going on.
Cara Curran was finishing the job when she witnessed what appeared to be a massive fight.
“There were women, men, old people, young people, such a mix of people, it didn’t feel real at the time.
“Working in the club scene for over two years, I’ve always seen a lot of fights, but it was nothing like tonight. The body language and the demeanor were quite different.”
“The amount of things that I heard happened during the three hour period tonight, with the stabbings, the traffic accidents and many other things that had a great impact on me.
“For me, being an eyewitness to something that happened was a very emotional night to the point where I’m still a little shocked.”
“Series of incidents”
Mayor Andy Street said he was informed by the police chief and was able to confirm that there had been “a series of incidents in the Hurst Street area.”
He added: “The rationale is yet to be understood. The area is quiet and the public has been told to go about their business but stay alert.”
West Midlands Police said: “We are aware of a number of injuries, but at the moment we cannot say how many or how serious.”
Police have established a cordon at the intersection of Hurst Street and Bromsgrove Street
She said emergency services were working together at the scene and making sure the injured received medical attention.
The statement continues: “Work is still in progress to establish what happened and it may take some time before we can confirm anything.
“At this initial stage, it would not be appropriate to speculate on the causes of the accident.
“Emergency services have well-established plans to deal with serious incidents. Our response is ongoing in central Birmingham and will be for some time. There are cordons in place and there are some road closures.”
The force later said there had been no reports of the shooting, adding: “We are aware of some comments that shots were fired, this has not been reported to us at this time.”
‘Stay very vigilant’
On Saturday night, many people were sitting outside eating and drinking.
Streets in the area were already closed to traffic due to coronavirus restrictions.
Sources said there was also some police activity at a second location in the Snow Hill area, about a 10-minute walk from the demarcated area, which is believed to be related to the Hurst Street incident.
Foreign Minister Dominic Raab said those in the immediate vicinity of the serious Birmingham accident must be “very vigilant.”
Speaking to Sky News’ Sophy Ridge Sunday show, Raab said: “My thoughts are with the victims and their families, obviously there is a police investigation underway.
“I can’t say much more at this point, but people should be very vigilant if they are in that area.”