The second victim of the UK terrorist attack that left three people dead and many more injured has been identified as a US citizen.
Joe Ritchie-Bennett, 39, was one of three people killed on Saturday in Forbury Gardens in Reading when a man armed with a knife began stabbing randomly at groups enjoying picnics in the sunshine.
Libyan man Khairi Saadallah, 25, was detained at the scene and arrested on suspicion of murder.
It is understood he had recently been released from prison and was known to Britain's MI5 security services.
Mr Ritchie-Bennett had been with his friend, history teacher James Furlong, who was also killed in the attack.
Mr Ritchie-Bennett grew up in Philadelphia but has lived in the UK for the past 15 years. He had been working for a Dutch pharmaceutical company with offices in Reading.
His father, Robert Ritiche, told Eyewitness News his son's murder was "senseless".
"The family is heartbroken they have lost their brilliant and loving son. This was senseless," he said.
US ambassador to the UK Woody Johnson confirmed that an American citizen was killed in the Reading atrocity.
"I offer my deepest condolences to the families of those killed in the attack on June 20," he tweeted.
"To our great sorrow, this includes an American citizen. Our thoughts are with all those affected.
"We condemn the attack absolutely and have offered our assistance to British law enforcement."
Mr Furlong's parents, Gary and Janet, have paid tribute to their son.
“James was a wonderful man. He was beautiful, intelligent, honest and fun," they said.
“He was the best son, brother, uncle and partner you could wish for. We are thankful for the memories he gave us all. We will never forget him and he will live in our hearts forever.”
On Monday, mourners held a minute's silence in Reading for the victims.
The Holt School where Mr Furlong worked was also closed for the day.
"As a Holt community, we all now need to absorb this sad news," co-principals Anne Kennedy and Katie Pearce said in a statement.
"He was determined that our students would develop a critical awareness of global issues and in doing so, become active citizens and have a voice.
"Words cannot describe our shock and sadness at this time.
"Our thoughts are with his mum, dad, brother and family, and his friends and colleagues. He was a cherished colleague and he will be sadly missed."
The incident happened at 7pm as families and groups relaxed in the park in Reading, which is 65 kilometres west of London.
Witnesses had described a man lashing out at groups of people with a knife.
He is believed to have then dropped the weapon and fled before police tackled him to the ground.
Personal trainer Lawrence Wort witnessed the attack and ran for his life.
“One lone person walked through, suddenly shouted some unintelligible words and went around a large group of around 10 trying to stab them," Mr Wort said.
“He stabbed three of them in the neck and under the arms, and then turned and started running towards me, and we turned and started running."
Police arrested asylum seeker Mr Saadallah in connection with the incident.
A western security source says he had been known to MI5 since last year.
Describing the incident as an atrocity and terrorism, police say they have detained the one man and are not searching for any others.
"What you appear to have here is a lone actor and they are obviously particularly hard to detect," said Jonathan Hall, the independent reviewer of terrorism legislation said.
When asked about the reports of the assailant being already on authorities' radar, Britain's Security Minister, James Brokenshire, said the government did not comment on intelligence matters.
In February, police shot dead Sudesh Amman in south London in a similar terror incident.
He stabbed two people and had been under counter-terrorism surveillance after his release from prison for terror offences.
Last November, another man who had been jailed for terrorism offences stabbed two people to death on London Bridge before he, too, was shot dead by police.