UK Police have declared a stabbing attack in which three people died a "terrorist incident".
Police secure a cordon near Forbury Gardens park in Reading, west of London, on June 20, 2020 following a stabbing incident. Photo: AFP
A 25-year-old man from Reading was arrested at the scene of the attack, which also left three people seriously injured.
Metropolitan Police Assistant Commissioner Neil Basu, head of counter-terrorism policing, said: "This was an atrocity."
He said police have found "nothing to suggest anyone else was involved".
Security sources told the BBC the man arrested is thought to be Libyan.
Basu said police were working with the coroner to formally identify those who had died and he praised the actions of unarmed Thames Valley Police officers, who detained the suspect.
He also praised members of the public who helped in the emergency and said 41 witnesses had so far come forward.
He said "the motivation for this horrific act is far from certain" but added it was clear that it was not associated with an earlier peaceful Black Lives Matter demonstration at Forbury Gardens, the site of the attack.
The attack happened at Forbury Gardens at about 7pm local time where several people were stabbed.
One eyewitness told the BBC he saw a man move from group to group stabbing people in the park.
There were reports that a police officer "rugby tackled" a suspect to the ground, according to the Sunday Mirror.
Police have asked anyone with mobile phone footage of the attack to come forward.
But people have been urged not to share videos and photos online "out of respect for the victims' families" after footage was circulated on social media.
Thames Valley Police said the incident was not connected to an earlier Black Lives Matter (BLM) protest in the park.
About a dozen armed police officers carrying shields were later seen entering a block of flats in Basingstoke Road in Reading at around 11pm local time.
Thames Valley Police Chief Constable John Campbell said it was a "truly tragic incident".
"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," he said.
Prime Minister Boris Johnson said his "thoughts are with all of those affected by the appalling incident in Reading".
"My thanks to the emergency services on the scene," he added.
Laurence Wort, 20, who was visiting Reading for the day on Friday, told the BBC he was about 10m away from the attack.
"A man walked along the path opposite where we were walking past a group of eight to 10 men, before darting to the left and going to stab three people in the first group.
"Changing direction, he runs towards us and then when we realises he's not going to catch us, he turned back and went for another group that hadn't realised what was happening yet, and he managed to stab someone in the second group," Wort said.
Home Secretary Priti Patel tweeted to say she was "deeply concerned" at the incident.
She said: "My thoughts are with everyone involved, including police and emergency responders at the scene."
Policing minister Kit Malthouse tweeted his "deepest sympathies to all affected" and described the incident as "horrific" and "dreadful".
Labour leader Sir Keir Starmer said the stabbing was "very concerning".
'Peaceful protest'
BLM organisers said the incident was unrelated to a protest march in the area earlier.
Nieema Hassan said in a video message posted to Facebook: "They were very peaceful and we worked with the police liaison.
"In terms of the protest and the people who attended from Black Lives Matter, we're all safe.
"None of us are affected. We had all left by the time this happened."
- BBC