EDMONTON—Prime Minister Justin Trudeau is condemning violent events in Edmonton as a “terrorist attack” following a chaotic night that saw a police officer stabbed and several pedestrians run down with a cube van.

Edmonton police said they have arrested a 30-year-old man and they think he acted alone. But police chief Rod Knecht stressed Sunday morning that the investigation is in its early stages and authorities haven’t ruled out others might have been involved.

An Edmonton police spokesperson said anything involving the suspect’s identity cannot be revealed at this time.

“When we believe, from a national security perspective, that a time is right to release his name, we’ll do that,” said Scott Pattison.

The police officer was taken to hospital and treated for non life-threatening injuries. He has since been released and is currently at home with his family, said Pattison.

Four people were injured by the van and rushed to hospital. The extent of their injuries was not immediately known. At last count, around 2 a.m., one individual was believed to be in critical condition, said Pattison.

“The individual made a concerted effort to run over people, pedestrians that were seemingly out to enjoy a lovely fall evening here,” he said.

Trudeau said Sunday that he was deeply concerned and outraged at what he called a “terrorist attack.”

“Our thoughts are with those injured, their family and friends, and all those affected by this senseless act of violence,” Trudeau said in a statement, in which he also thanked first responders and law enforcement.

“While the investigation continues, early reports indicate that this is another example of the hate that we must remain ever vigilant against.

“We cannot — and will not — let violent extremism take root in our communities. We know that Canada’s strength comes from our diversity, and we will not be cowed by those who seek to divide us or promote fear.”

In a prepared statement published Sunday morning, Alberta Premier Rachel Notley called the incident horrific.

“It’s left us shocked at the indiscriminate cruelty and angry that someone might target their hatred at places where we gather with our families and friends,” it reads. “As we learn more about what happened last night, I encourage everyone to remain vigilant and to listen to law enforcement authorities.”

Edmonton Mayor Don Iveson asked for calm during a morning press conference.

“To my fellow Edmontonians, it is vital now that we do not succumb to hatred. That we not be intimidated by violence … We will not be divided,” he said. “Terrorism is about creating panic and sowing divide and disrupting people’s lives. We can succumb to that or rise above it.”

Iveson added that the suspect is in-custody and is being interviewed “as we speak.”

“I’m confident that our law enforcement is in full authority and their investigation is progressing well,” he said. “This appears to be a lone wolf incident. The city takes very seriously the safety of its citizens. Violence like this is abhorrent in our community.”

Iveson said he’s suspended his campaign until there’s resolve, that further risks and threats are being monitored at the federal level.

It all began Saturday night, around 8:15 p.m., outside the Edmonton Eskimos CFL football game at Commonwealth Stadium where it was military appreciation night.

Canada’s chief of defence staff, Gen. Jonathan Vance, conducted the pre-game coin flip and two CF-18 fighter jets did a flypast before kickoff. More than 800 Boy Scouts were expected at the game and many were planning to camp out on the field afterward.

While the Eskimos were battling the Winnipeg Blue Bombers inside the stadium, outside a white Chevy Malibu approached a traffic control post at a high speed.

In a video released by police, a white car is shown bursting through a barricade, hitting the stationed police officer and hurling him onto the side walk. The incident lasts about three seconds, ending with the car colliding into a police cruiser.

Knecht said the car threw the officer about five metres into the air.

The driver hopped out and began “viciously” stabbing the officer with a knife before running away, Knecht said. Police launched a manhunt for the suspect.

Knecht said a Daesh flag was found in the front seat of the car and was seized as evidence.

A few hours later, while fans filed out of the game and were rerouted around the crime scene, a U-Haul cube van was stopped at a checkstop north of downtown.

When the driver was asked for his licence, Knecht said the name on the identification was close to that of the registered owner of the white Malibu.

When confronted, Knecht said the U-Haul sped off toward downtown with police cars in pursuit.

The van intentionally swerved at pedestrians in crosswalks, Knecht said.

“It is believed at this time that these two incidents are related,” Knecht said. “These incidents are being investigated as acts of terrorism.”

The name of the suspect was not released. Knecht said he was known to police, but there was no warning for the attack.

In a tweet Sunday, Public Safety Minister Ralph Goodale said “Canada will not be intimidated by terrorist violence.”

Goodale’s office issued a statement to say the RCMP’s Integrated National Security