A man accused in a terror-related stabbing spree that killed three people and seriously injured three others in a British park Saturday was known to the U.K.’s counter-intelligence agency, according to a report.

Police have not named the 25-year-old suspect, but Britain’s BBC and other British media outlets identified him as a Libyan asylum-seeker living in Reading, a town west of London where the rampage unfolded Saturday evening.

The man had caught the attention of MI5, Britain’s domestic counter-intelligence and security agency, in 2019 over concerns he planned to travel abroad to join a jihadi group, security sources told the BBC. But, he was not determined to be a major threat and the agency did not open a case file on him, the sources said.

Overnight, heavily armed officers raided an apartment about a mile away from the park, where the suspect reportedly was living. After everyone living there evacuated, a loud bang was heard from inside the building. (Steve Parsons/PA via AP)

UK STABBING ATTACK THAT LEFT 3 DEAD BEING TREATED AS TERROR INCIDENT, POLICE SAY

Police took the 25-year-old into custody within five minutes of arriving at the “horrific” scene in Reading’s Forbury Gardens Park. Investigators said they believed he was the lone attacker and there was no further danger to the public.

Lawrence Wort, a personal trainer who witnessed the attack, said the park was crowded when one person suddenly “shouted some unintelligible words and went around a large group of around 10, trying to stab them.”

Wort continued, “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.”

An aerial view showing blue police tents Sunday in Forbury Gardens, the scene of a stabbing attack in Reading on Saturday. (Jonathan Brady/PA via AP)

Police blocked and patrolled streets leading to the park on Sunday. Mourners left notes and bunches of flowers by the police tape in tribute to the victims.

UK SUSPECT ARRESTED  AFTER STABBING ATTACK, POLICE SAY

One of the people killed was identified as James Furlong, a teacher in the nearby English town of Wokingham. Furlong’s colleagues and former pupils described him as a “kind and gentle man” and “really incredible teacher,” Sky News reported.

Police officers collecting flowers left at the Abbey gateway of Forbury Gardens on Sunday, one day after the stabbing attack. (AP Photo/Alastair Grant)

Prime Minister Boris Johnson, who met security officials, police and senior ministers on Sunday for an update on the investigation, said he was “appalled and sickened” by the attack.

“If there are lessons that we need to learn” or legal changes needed to prevent such attacks, “then we will learn those lessons and we will not hesitate to take action where necessary,” Johnson said.

Officials have not released further details on the suspect.

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However, a Reading man of the same reported name and age as the suspect was sentenced to two months in prison last year for assaulting an emergency worker, The Associated Press reported. The same man reportedly also was charged last year with assaulting a judge who had sentenced him.

The Associated Press contributed to this report.