A stabbing incident in Reading on Saturday which left three people dead and three seriously injured has been declared a terrorist incident, police have confirmed.

The attack took place at around 7pm in Forbury Gardens in Reading’s town centre.

One of the patients admitted to hospital has been discharged, while another remains in a stable condition under observation at Royal Berkshire Hospital, a spokesperson said. 

Thames Valley Police have confirmed the attack is now being treated as terrorism and that counter-terror police would now be taking over the investigation.

Boris Johnson said he was “appalled and sickened” by the attack and pledged “we will not hesitate to take action” if there are lessons to be learned.

Speaking to BBC News, Johnson said: “I don’t want to preempt the work of the police and their investigation into what happened in this case.

“If there are lessons that we need to learn about how we handle such cases we will learn those lessons and we will not hesitate to take action where necessary.”

He said these could include “changes to the legal system” in order to try to prevent future attacks from taking place, although he said there was no reason to believe there could be more terror attacks as lockdown restrictions are eased.

Assistant commissioner at Metropolitan Police, Neil Basu, said 41 witnesses had come forward following the attack.

In a statement at New Scotland Yard, he described the stabbings as an “atrocity” and sent his “deepest sympathies” to the family of the three people who died and those who have been injured.

He added there was nothing to suggest anyone else was involved and police are not currently seeking anyone else as part of the investigation.

He said: “From our inquiries undertaken so far, officers have found nothing to suggest that there was anyone else involved in this attack and presently we’re not looking for anyone else in relation to the incident.

“However, counter-terrorism detectives work closely with the security services and will work closely with Thames Valley major crime colleagues and we continue to make inquiries to ensure that is the case.

“Although the motivation for this horrific act is far from certain, counter-terrorism policing have taken responsibility for leading the investigation.

He said the public should not be alarmed when out in crowded places and counter terror police would be working “around the clock”. 

Basu added the incident was not connected to a Black Lives Matter (BLM) protest that took place earlier in the day in the park. 

He said: “We’re clear that it was not associated in any way with the Black Lives Matter protest which took place peacefully earlier on in the day and which had concluded some hours before this attack took place.”

Police said a 25-year-old man from Reading who was arrested at the scene on suspicion of murder remains in custody. 

A statement issued on the Thames Valley Police website said: “Counter Terrorism Policing can now confirm that the stabbing incident that happened in Reading last night (20/6), has now been declared a terrorist incident.

“Officers from Counter Terrorism Policing South East (CTPSE) have been working closely with Thames Valley Police’s Major Crime Department throughout the night.

“Deputy Assistant Commissioner Dean Haydon, Senior National Coordinator for the Counter Terrorism Policing network, has this morning declared the incident a terrorist incident, and CTPSE will be taking over the investigation.”

Thames Valley Police chief constable, John Campbell, described the scene of the attack in Reading as “horrific”.

He told reporters: “As you can imagine the scene we came across was pretty horrific.

“We had a number of officers that were in the community because they were patrolling around Reading and they were there very quickly.

“We also had a number of people in the park that were witnesses to this incident and they saw the terrible tragedy unfold.

“So you can imagine both for my officers but also for those that were involved it was very distressing and we are doing all that we can to make sure we are supporting them as well as progressing the criminal inquiry.”

He did not identify the victims and said Thames Valley Police were still in the process of contacting their next of kin.

Floral tributes were left to the victims near the scene of the incident.

One read: “There are no words that anyone can say to express how horrible and senseless this was.

“Our prayers are with all the victims and their families and friends. #Readingstandsunited.”

Editor’s note: A subsequent article containing PA Media reporting of details about the suspect has been redirected to this article.