A man has been arrested on suspicion of murder after one person died and seven others were injured in stabbings across Birmingham city centre.
The 27-year-old suspect was arrested at an address in the Selly Oak area of the city at about 04:00 BST, West Midlands Police said.
Officers said he was also being held over seven counts of attempted murder.
The attacks happened at four Birmingham locations over a period of 90 minutes in the early hours of Sunday.
Forensic officers have been seen conducting searches at an end-of-terrace house in a cul-de-sac in Selly Oak, where neighbours said a police raid took place in the early hours.
Eyewitness Robert McLeod, who said he saw two men and a woman walking, stated: "He looked like he just wanted to walk through them.
"But the three people obviously stopped, cos... when someone's walking in, you sort of get out the way.... He just launched at her chest and neck and started stabbing at her chest and neck.
"The armed response... comes to me and I say 'look, he's gone down there, it's a dead-end street' so they went down, but they couldn't find him."
Selly Oak resident John Astley said he was woken by a loud bang during the night and saw a police van parked outside the neighbouring property.
He said: "I think there were three people living there. They have only been there a few months, since July or something like that.
"I had a look out of the front bedroom window and I just noticed there was a police van. I could hear a lot of noise coming from next door and it sounded like they were doing a search."
Officers were first called out just after 00:30 on Sunday at Constitution Hill, where a man sustained a superficial injury.
About 20 minutes later they were called to Livery Street, near Snow Hill railway station, where a 19-year-old man was critically injured and a woman was also hurt.
At 01:50, police were sent to Irving Street, where a 23-year-old man suffered fatal injuries and another man was seriously hurt.
Ten minutes later, they were called to Hurst Street, in the city's Gay Village, where a 32-year-old woman was critically injured and two men were less badly hurt.
Police say they are treating the attacks as "random" at this stage.
Ch Supt Steve Graham said: "Officers worked through yesterday and into the early hours of this morning in a bid to trace the man we believe responsible for these terrible crimes.
"We issued CCTV footage of the suspect and had a strong response from the public. I'd like to thank everyone who shared our appeal and who provided information to the investigation.
"Clearly this is a crucial development but our investigation continues."
A hotline number and website have been set up for members of the public to provide information, while some streets remain closed on Monday as investigations continue.
Julia Robinson, the manager of Birmingham Southside Business Improvement District, described the "chaos" she saw as events unfolded on Sunday.
"I run a warden service in the city and they stand down at about midnight but that night it had been quite busy so we were getting them taxis from a local venue at about 1:30 to 1:45.
"We heard the screaming then a lot of people running and went outside to see what was going on.
"There was a man and a couple that had been injured, a man covered in blood, there was a girl on the ground who appeared to be bleeding quite profusely, people trying to help her.
"Then it was a case of standing back and we were doing our bit really to help with crowd control and to try and get everyone out of the area so the emergency services could do their job."
Questions have been raised about how the suspect was able to move around the city for 90 minutes.
Birmingham MP Shabana Mahmood said she "shares the same concerns as everybody else", but the priority was supporting the police with their investigation.
She said: "There will be a more appropriate stage to have a more forensic sort of detail about the way that the incident unfolded, and also the police response, and I will certainly be asking those questions as well.
"But for now I'm encouraged... the police have described a strong response to their CCTV footage appeal."
West Midlands mayor Andy Street told BBC Radio 4's Today programme it was not right to say the police response was too slow.
"It's very easy to comment on a police investigation while it's live. I don't intend to fall into that trap," he said.
"[There are] lots of questions as to what happened during that two-hour period, but there's people making lots of assumptions from things that they quite frankly don't know."
He also said what happened in the early hours of Sunday "does not define Birmingham".
"We have to see it as a one-off random [incident], and what will define the city is our response to it now," he said.
West Midlands Police and Crime Commissioner David Jamieson said the events had left the city "in shock".
"I'm pleased officers moved so quickly to compile and analyse the evidence available to track down the suspect and make an arrest. I hope this offers some comfort to the people of the West Midlands who have been so understandably worried.
"I'd also like to place on record my sincere thanks to the brave and hardworking police, hospital and ambulance staff who have acted so quickly to help the victims of this atrocity. My thoughts are with all those affected."
Extra officers from the neighbouring Staffordshire and West Mercia forces were deployed in the city centre on Monday.