Amman was sentenced to three years and four months but under current British laws was last month automatically released halfway through his sentence. He has since been under police surveillance.
In the terror trial, it was revealed that Amman, then aged 18, had advised his girlfriend to kill her “kuffar” parents.
Amman told her: “If you can’t make a bomb because family, friends or spies are watching or suspecting you, take a knife, molotov, sound bombs or a car at night and attack the tourists [crusaders], police and soldiers of taghut, or Western embassies in every country you are in this planet.” Amman was also found with a bomb-making manual.
Footage from the attack in Streatham, south London, shows a group of heavily armed officers shielding behind a car with their guns drawn. A man’s body is seen lying on the footpath.
After officers inspected the body, they quickly retreated.
Police later said the man had been shot and pronounced dead at the scene.
“A device was found strapped to the body of the suspect and specialist officers attended,” Deputy Assistant Commissioner Lucy D’Orsi said in a statement.
“Cordons were put in place and it was quickly established that this was a hoax device.
“The incident was quickly declared as a terrorist incident and we believe it to be Islamist-related.”
Student Gulled Bulhan said the shooting happened in front of a pharmacy on Streatham High Road.
“I was crossing the road when I saw a man with a machete and silver canisters on his chest being chased by what I assume was an undercover police officer as they were in civilian clothing,” the 19-year-old told the PA news agency.
“The man was then shot. I think I heard three gun shots but I can’t quite remember.”
Streatham resident Nardos Mulugeta said he heard gunshots and saw one victim lying in the street.
“I went over and I saw the first victim – a male victim – on the ground near the White Lion Pub, and people were helping him,” the 52-year-old said.
“Then five minutes later a woman came over and said ‘I’ve been stabbed too in the back’. And then people starting helping her.
“I saw one body laying down further away. He was face down between [the shops] Argos and Iceland. It’s really scary.”
Police later said that one victim, a man in his 40s is no longer in a life-threatening condition. A woman in her 50s has been discharged from hospital. Another woman, in her 20s who had minor injuries resulting from police fire is still being treated.
Deputy assistant police commissioner Stephen Roberts said police were looking to search the suspect’s home and seize any computer-based evidence that could provide clues to a motive.
Investigators were researching the man’s background to learn more about the attack and any possible co-conspirators, Roberts said.
He said that if evidence suggested the stabbings were carried out by a “self-starter”, it meant that any city in the country was vulnerable at any time to a similar “low-tech” attack.
A video posted on social media shows a policeman attempting to evacuate a nearby shop, although cafe staff appear initially reluctant to leave. The staff and customers eventually follow the police officer’s instructions after he explains the suspected terrorist is believed to be wearing an explosive device.
Prime Minister Boris Johnson was briefed on the attack on Sunday afternoon.
“Thank you to all emergency services responding to the incident … which the police have now declared as terrorism-related,” he said. “My thoughts are with the injured and all those affected.”
“Terrorist seek to divide us and to destroy our way of life [but] here in London we will never let them succeed,” the city’s mayor, Sadiq Khan, said in a statement.
The UK’s terror alert level remains at “substantial”, which means an attack is likely.
Confirmation of a terrorist motive would make this incident the third terror attack in the United Kingdom in two months.
British police shot a man dead on London Bridge following a stabbing rampage that killed two people and wounded three others in late November. The attacker, 28-year-old Usman Khan, had been previously convicted of terrorism offences and released from prison in 2018.
Khan was free on parole, with an electronic tracking device on his ankle, when he entered a conference focused on the rehabilitation of violent offenders and terrorists. Khan slashed at his victims with knives and wore a fake suicide vest. He had been previously convicted of conspiring to bomb London landmarks.
In early January, two inmates wearing fake suicide belts attacked and seriously wounded a guard at the Whitemoor maximum security prison in Cambridgeshire.
In a June 2017 attack, three Islamic State sympathisers were shot and killed after ramming pedestrians with a van near London Bridge and stabbing eight bystanders to death in nearby Borough Market. Another 48 people were wounded.
In March 2017, British citizen Khalid Masood was shot dead after ploughing his car into pedestrians on Westminster Bridge and then fatally stabbing a police officer.
– with agencies
Bevan Shields is the Europe correspondent for The Sydney Morning Herald and The Age.