A man has died and seven people have been left injured after multiple people were stabbed in the city centre in the early hours of Sunday morning.
Police are still searching for the suspect involved.
West Midlands Police confirmed that a 23-year-old man had suffered fatal injuries in Irving Street, while a man and a woman – aged 19 and 32 – were critically injured.
Another five people, aged between 23 and 33, were also injured, officers said. They were treated in hospital and so far two have been discharged.
Police have now released CCTV footage of a man they want to speak to following the incident.
Chief Superintendent Steve Graham said: “We do not underestimate the impact that these incidents have had on the city of Birmingham today.”
“Scores of officers” have been drafted in to help with the investigation and to patrol the city to reassure residents, he said.
“We have worked throughout the day to trawl CCTV footage and speak to witnesses to ensure we release the best possible video and image of the man we want to speak to.
“At this stage we believe that the attacks were random and we have no indication of a motive. I would urge people to remain vigilant and report any suspicious behaviour to us.
“We are appealing for anyone who recognises the man in the footage to contact us urgently.”
West Midlands Police declared a major incident after being called to reports of a stabbing just after midnight on Sunday, before more calls came in of further attacks.
Earlier on Sunday, Graham said the incidents appeared to be “random”, with “no suggestion” the night’s events were linked to terrorism.
Home secretary Priti Patel tweeted: “All my thoughts are with those affected by the shocking incident in Birmingham last night.
“Our emergency services are working hard to find whoever is responsible and bring them to justice.”
Speaking to Andrew Marr on BBC One earlier on Sunday morning, foreign secretary Dominic Raab said: “We know it’s a very serious incident. Our thoughts and prayers are with the victims and their families.
“I think at this point in time we don’t know too much more than that other than to say the public should be very vigilant.”