LONDON >> A knife-wielding assailant stabbed two college students to death in the streets of the English city of Nottingham and then fatally stabbed a middle-aged man, stole his van and ran down three pedestrians in a shocking rampage early Tuesday morning, police said.

Police arrested a 31-year-old man on suspicion of murder. The Nottinghamshire Police force said investigators believe the perpetrator acted alone and detectives were working with counterterrorism officers to try to establish a motive.

“This is a horrific and tragic incident which has claimed the lives of three people,” Chief Constable Kate Meynell said.

A man who was among the people struck in the hit-and-run was hospitalized in critical condition. The dead included two 19-year-old students from the University of Nottingham.

“All of us at Nottingham are deeply shocked and saddened by the deaths of two of our students,” Vice Chancellor Shearer West said in a statement.

A graduation ball scheduled for Tuesday evening was canceled. Many college students joined a vigil at St. Peter’s Church, in the city center, late Tuesday to mourn the victims. Some lit candles, while others laid flowers beneath the altar.

The knife attack on the students occurred around dawn in an area near student housing a short walk from the university’s Jubilee Campus. A caller reported that two stabbing victims were lying in the street.

Police think the attacker then killed a man in his 50s and took his van, Meynell said. His body was found on a different street more than a mile from the first crime scene.

About 90 minutes after the initial attack, witnesses were horrified as they watched the van plow into pedestrians and flee.

Lynn Haggitt was on her way to work when a white van pulled up beside her at 5:30 a.m. She saw the driver look in his mirror and spot a police car approaching slowly from behind without its emergency lights on. The driver then accelerated and struck a man and woman at a street corner, she said.

“He went straight into them. He didn’t even bother to turn,” Haggitt told reporters. “The woman went on the curb, the man went up in the air, there was such a bang, I wish I never saw it. It’s really shaken me up.”

The driver then sped through the city center with police on his tail, she added.

Haggitt said the wounded man appeared to have a head injury but was helped to his feet. The woman was sitting on the curb and appeared to be OK. A third pedestrian was struck on the same street, police said.

Two of the hit-and-run victims had minor injuries, Meynell said.

“We believe these three incidents are all linked, and we have a man in custody,” the police chief said. “We are keeping an open mind as we investigate the circumstances surrounding these incidents and are working alongside Counter Terrorism Policing to establish the facts, as we would normally do in these types of circumstances.”

After stopping the van, officers subdued the suspect with a Taser before detaining him.

University of Nottingham student Kane Brady said he awoke to loud shouts of “armed police” and heard what sounded like a gunshot outside.

He said he saw officers holding stun guns and a man being dragged out of the van and pinned on the ground.

“I saw him getting arrested, him trying to resist,” Brady told British broadcaster GB News. “When they opened the van, I saw a large knife being pulled out and then straight away, that’s when police closed off both roads.”

Photos showed the hood of the van dented and cracks in the windshield.

British Prime Minister Rishi Sunak called it a shocking incident and asked that police be given time to investigate the crime.

“My thoughts are with those injured, and the family and loved ones of those who have lost their lives,” Sunak said.

Nottingham is a city of about 350,000 people some 110 miles (175 kilometers) north of London.

Images on social media showed police, some with rifles, standing near cordons at several locations in the city center.

The city’s tram network said it suspended all services.