LONDON — A stabbing attack at a park in southern England that left three people dead on Saturday is being investigated as a “terrorist incident,” police officials said Sunday.
The attack happened around 7 p.m. at Forbury Gardens in the town of Reading, the Thames Valley Police said. A Black Lives Matter protest had been held there earlier in the day, though the police said earlier that the stabbings were not connected to the demonstration.
Three people were killed in the attack and three more were seriously injured, the police said. A 25-year-old man was arrested at the scene on suspicion of murder on Saturday and remained in custody on Sunday.
“Incidents of this nature are very rare, though I know that will be of little comfort to those involved and understand the concern that this incident will have caused amongst our local community,” Chief Constable John Campbell said in a statement on Sunday.
The Thames Valley Police said that counterterrorism units would be taking over the investigation.
Counter Terrorism Policing said in a statement on Sunday that there was nothing to suggest that other people were involved. Neil Basu, assistant commissioner specialist operations, said that “the motivation for this heinous act is far from certain.”
It is the deadliest terror attack in Britain since 2017, when eight people were killed after three men in a van drove into pedestrians on London Bridge before stabbing people in a nearby market.
Britain has seen a string of recent attacks classified as terrorism. In February, a man who wore a fake explosive device strapped to his body was killed by the police in Streatham, in South London, after he stabbed two people. Earlier, in January, inmates stabbed staff members at a prison in Cambridgeshire, while two people were fatally stabbed near London Bridge in November.
In an interview on Sky News on Sunday, Prime Minister Boris Johnson on Sunday praised the police for their bravery and said he was “appalled and sickened” by the assault.
“If there are lessons that we need to learn about how we handle such cases, how we handle the events leading up to such cases, then we will learn those lessons and we will not hesitate to take action when necessary,” he said.
Lawrence Wort, a 20-year-old personal trainer who said he was at the park at the time of the attack, described what he experienced in a message on Twitter on Saturday.
“The park was pretty full, a lot of people sat around drinking with friends when one lone person walked through, suddenly shouted some unintelligible words and went round a large group (of about 10 people) trying to stab them,” he said.
He added that the man’s eyes “looked like he was on some sort of drugs” and said that he stabbed three people in the neck and under the arms before turning and running toward Mr. Wort, who said he ran to escape.
The assailant then turned to another group of people who were sitting down, and stabbed one of them in the back of the neck, according to Mr. Wort. When he realized that everyone had started to run, the attacker left the park, he said.
Despite early social media posts that said the attack happened during the Black Lives Matter protest, Mr. Wort said that the protest had ended at least three hours before the stabbings.
This claim was also supported by Nieema Hassan, one of the organizers of the Black Lives Matter protest at Forbury Gardens, who said in a video message on Facebook on Saturday that the attack had nothing to do with the protest and that none of the protesters were affected as they had all left the park.
“This evening we saw a senseless attack on people simply enjoying a Saturday evening with family and friends,” the British home secretary, Priti Patel, said in a statement early Sunday. “My heart, prayers and thoughts are with all of those affected and to the people of Reading who will be deeply shocked and concerned by this terrible incident.”