A 23-year-old man who was stabbed to death in Birmingham city centre has been named as Jacob Billington.
Mr Billington was attacked in Irving Street in the early hours of Sunday while he was out with old school friends, police said.
Seven other people were injured at four locations over a period of 90 minutes.
A 27-year-old man has been arrested on suspicion of murder and attempted murder.
West Midlands Police said Mr Billington, from Crosby, Merseyside, was on a school reunion night out with friends.
One of the group, also 23, was seriously injured and remains in hospital in a critical condition.
In a statement Mr Billington’s family said: “Jacob was the light of our life and we have been devastated by his loss.
“He was a funny, caring and wonderful person who was loved by every single person he met.
“He lit up every room with his boundless energy and witty humour and the loss of such a special person will be felt by all who knew him for years to come.”
Police were first called out just after 00:30 BST on Sunday at Constitution Hill, where a man sustained a superficial injury.
About 20 minutes later they were sent to Livery Street, near Snow Hill railway station, where they found a 19-year-old man with critical injuries and a woman who was also hurt.
At 01:50, officers were despatched to Irving Street, where Mr Billington was found with fatal injuries and his friend seriously hurt.
About 10 minutes later, police were called to Hurst Street, in the city’s Gay Village, to find a 32-year-old woman had been critically injured and two men less badly hurt.
The suspect was arrested at an address in the Selly Oak area of the city at about 04:00 on Monday and remains in custody.
Three other people, two men and a woman, from the same property were arrested on suspicion of assisting an offender.
Ch Supt Steve Graham said: “Our thoughts and sympathies are with Jacob’s family and friends after receiving such shocking news, particularly for those who were sharing their night out with him.
“It’s utterly shocking that a friends’ reunion should end so brutally.
“Equally the families of the other victims have been left devastated by the events of Sunday morning and we are working hard to discover what led to the apparently random attacks.”
Questions have been raised about how the suspect was able to move around the city for 90 minutes.
Responding to this, Chief Constable Dave Thompson said: “Engaging in an ill-informed critique of this investigation, particularly at such an early stage, is both unhelpful and simply makes the job of the police harder.”
Mr Thompson described the knife attacks as “extraordinary”, adding: “These are events quite unlike anything I have seen on our streets before.”