Police have been given another 36 hours to question the suspect in the Nottingham attacks in which three people died.
The 31-year-old man was arrested at about 05:30 BST on Tuesday.
The victims were University of Nottingham students Barnaby Webber and Grace O’Malley-Kumar, both 19, and caretaker Ian Coates, 65.
Police said the suspect was a former student of the university but did not believe this to be behind the attack.
Nottinghamshire Police also confirmed it had referred part of the incident to the Independent Office for Police Conduct (IOPC), as a marked police car followed the suspect’s van before it collided with two pedestrians.
Mr Webber and Ms O’Malley-Kumar were attacked with a knife in Ilkeston Road, shortly after 04:00.
After this a man matching the suspect’s description attempted to get into a supporting living complex in Mapperley Road, but was unable to gain entry.
Police believe that shortly afterwards, he attacked Mr Coates – who was found dead from knife injuries in Magdala Road – and stole his van, which was then used to hit pedestrians.
Officers have given more details of three other people injured in this part of the attacks.
Police said a man run over in the Milton Street area remained in a serious condition in hospital.
An attempt was then made to run over two other pedestrians in the Sherwood Street area. They are believed to have suffered minor injuries.
It was this part of the attacks that prompted the referral to the IOPC, police confirmed.
The IOPC confirmed the move and said: “We are assessing the referral to decide what further action may be required of the IOPC.”
The suspect was Tasered and arrested after leaving a van and approaching officers with a knife, police said.
The force said it was still working alongside counter-terrorism policing and keeping an “open mind” on the motives behind these attacks.
A statement added: “A team of dedicated detectives is continuing to question the suspect and building up a strong picture of what happened that morning.
“This has included CCTV gathering, forensics, eyewitness accounts and searching a number of properties in the city.”