Video has been released of a man police are searching for following a stabbing rampage in Birmingham last night.
West Midlands Police officers have spent the day trawling through CCTV and speaking to witnesses of the knife attack.
Eight people were injured and one killed in the mayhem. The killer is still at large.
Chief Superintendent Steve Graham 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.
"We have a hotline number and a dedicated web page where you can submit information, photos and videos.
"If you see him, please do not approach him, but dial 999 immediately."
The CCTV footage shows a man wearing a baseball cap, and wearing a dark hoodie with distinctive white drawstrings.
Police said a 23-year-old man suffered fatal injuries in Irving Street.
A man and a woman, aged 19 and 32, suffered critical injuries, and five other people, aged between 23 and 33, were also injured.
They were treated in hospital and so far two have been discharged.
Mr Graham added: "We do not underestimate the impact that these incidents have had on the city of Birmingham today.
"We declared this a major incident at the earliest opportunity and we have drafted in scores of officers to help with the investigation and patrol the city to reassure residents and visitors that we are doing all we can to apprehend the person responsible."
Detectives are now racing to catch a male suspect who managed to evade capture last night, with "significant resources" now deployed, said senior police officers.
On Twitter, Prime Minister Boris Johnson thanked the emergency services.
He tweeted: "All my thoughts are with those affected by the terrible incident in Birmingham last night."
Home Secretary Priti Patel also said "all her thoughts" were with people affected by the "shocking incident" in the city.
"Our emergency services are working hard to find whoever is responsible and bring them to justice," she tweeted.
Mr Graham said initial calls were to reports of a stabbing in Constitution Hill around 12.30am, and then at the nearby Livery Street next to Snow Hill railway station.
Paramedics said they responded to first reports of a call in Livery Street, in the north of the city centre, at about 12.40am.
The attacker then moved "north to south" through the city centre, said Mr Graham, into the heart of the city's Gay Village quarter.
However, it was over an hour between the Livery Street violence and the next attack in Irving Street, across the city, at 1.52am which left a man fatally injured.
Shortly afterwards, the emergency services were called to another knife assault in Hurst Street at 2am.
