Two of those killed were 19-year-old students and the other victim was a man in his fifties.

One person is also in a critical condition after a van drove at people in the city centre.

A 31-year-old man has been arrested on suspicion of murder as police say they are keeping an open mind about the motive.

Here's a timeline of how the attacks unfolded.

Just after 4am - Two students stabbed in Ilkeston Road

Two young people are found dead by police following a call from a member of the public.

A witness told the BBC he saw a young man and young woman being stabbed and heard "awful, blood-curdling screams".

"I saw him stab the lad first and then the woman," the witness said.

"It was repeated stabbing - four or five times. The lad collapsed in the middle of the road.

"The girl stumbled towards a house and didn't move. The next minute she had disappeared down the side of a house, and that's where they found her."

5.30am - Van drives into people in Milton Street

A van tries to run three people over in the city centre, just over a mile from Ilkeston Road.

One witness, Frances, told Sky News she was on her way to work when she heard a bang that sounded like a car hitting a bollard.

"I turned around and then saw the two people on the floor, on the road," she said.

"Someone was screaming, I think a gentleman ran over to help as well.

"The van was still there, and then moments later the van took off and then the police arrived.

"I ran over to see how the two people were, just to see what I could do to help.

"There was a male and a female. The female - she could speak, she was in pain from the impact of hitting the ground. She had hit her head as well. She was still able to speak.

"The gentleman, I think, took the full brunt of the van, and he had head injuries but was still awake, he didn't lose consciousness at that stage."

Three people were injured and one of them was in a critical condition.

Around 5.30am - Man arrested in Bentinck Road

People living in Bentinck Road, about 1.5 miles from Milton Street, said police dragged a man out of a white van.

Footage showed a man being detained outside a convenience store.

Demi Ojolow, a student who lives in the road, said: "I just saw the police shouting at him to get out of the car and get on the floor.

"And they dragged him out of the car and he just fell on the floor. He was still pretty wrestling at the point.

"They dragged him away and that was about it."

Ms Ojolow said police were pointing some kind of weapon at the man - it's later confirmed that he was tasered.

7.04am - Police declare 'serious incident'

The first official announcement came from Nottingham Police, who said emergency services were at an "ongoing serious incident".

They asked people to avoid road closures in the city centre.

9.37am - Arrest of suspect announced

Police confirm a man, 31, has been arrested in suspicion of murder.

Shortly before 1pm - Armed police take away two women

Two women were taken away in a police van from Ilkeston Road - the site of the student stabbings.

A witness told Sky News that armed officers, some wearing balaclavas, were on the road a few hundred yards above the main cordon.

Police appeared to enter a commercial property in the street, with the two women eventually put in the back of a marked patrol car.

6pm - Police say suspect killed man and used van as weapon

Chief Constable Kate Meynell tells reporters they believe the van used to drive into people was stolen from one of the victims, a man in his 50s.

A member of the public found him dead from knife wounds in Magdala Road.

7.30pm - One of the victims is confirmed as 19-year-old University of Nottingham student Barnaby Webber.

It comes shortly after hundreds of students attended a church vigil where flowers were left and many people were in tears.

A card left in the church was made out to 'Grace' - but the identities of the other people killed have not yet been confirmed.