Three people were killed and three seriously hurt Saturday in a summer-evening stabbing attack in a park in the English town of Reading, police said. They said it was “not currently” being treated as a terrorism and the motive was unclear.

Thames Valley Police force said officers arrested a 25-year-old local man at the scene and they were not looking for anyone else.

“There is no intelligence to suggest that there is any further danger to the public,” said Detective Chief Superintendent Ian Hunter.

“This is not currently being treated as a terrorism incident; however, officers are keeping an open mind as to the motivation for the incident,” Hunter added. He said detectives from the counter-terrorism unit were supporting the investigation.

British media had earlier reported that police suspected a terrorist motive and that the man arrested was Libyan. Police did not confirm that or release the suspect’s name.

Prime Minister Boris Johnson said his “thoughts are with all of those affected by the appalling incident in Reading.”

The violence erupted around 7 p.m. as families and friends were enjoying a warm, sunny evening in the Forbury Gardens park in Reading, a town of about 200,000 residents 40 miles (64 kilometers) west of London.

Witnesses reported that police cars and helicopters descended on the park. Within minutes police had blocked off several roads, and two air ambulances landed nearby.

Personal trainer Lawrence Wort said the park was full of groups socializing on the grass when “one lone person walked through, suddenly shouted some unintelligible words and went around a large group of around 10, trying to stab them.”

“He stabbed three of them, severely in the neck, and under the arms, and then turned and started running towards me, and we turned and started running,” Wort said. “When he realized that he couldn’t catch us, he tried to stab another group. He got one person in the back of the neck and then when he realized everyone was starting to run, he ran out the park.”

Police said that “a number of people were injured and taken to hospital. Tragically, three of these people died, and another three sustained serious injuries.”

The Royal Berkshire Hospital in Reading said it was treating two casualties from the incident.

The incident came hours after a Black Lives Matter demonstration at Forbury Gardens, but police said there was no connection between the attack and the protest.

Nieema Hassan, one of the organizers of Saturday’s protest, said demonstrators had left by the time the violence occurred. In a social media post, she said she was “praying for the people that are affected. I hope they’re OK.”

Britain’s official terrorism threat level stands at “substantial,” the middle level on a five-rung scale, meaning an attack is likely.

It had previously stood a notch higher for several years. The country has been hit by a series of violent attacks in recent years, including a suicide bombing at an Ariana Grande concert in Manchester in 2017 that killed 22 people and two deadly vehicle and knife attacks in London the same year.

Airline worker Carlos Garcia Pascual was walking to his home near Forbury Gardens when emergency vehicles and police officers descended. He said it was “chaos” as police yelled at people to leave the area.

“We didn’t know if it was a situation like happened in London a few years ago, where the attackers were on the loose,” he said. “Forbury Gardens is a peaceful place, a lot of families go there with their kids to play, picnics. To realize that happened in Forbury Gardens is really hard to believe.”

(AP)