At about 14:00 GMT on Sunday, two people were stabbed on Streatham High Road, a busy shopping street in a residential area of south London.

Witnesses reported that a man had grabbed a knife from a nearby location and attacked at least two people with it. It also became clear that he was wearing what was described as a belt with canisters, giving the impression that he might be carrying an explosive device.

Very soon after that, the road filled with police officers in plain clothes and shots were fired.

Moments later, the man, who London's Metropolitan Police force said was believed to be Sudesh Amman, was declared dead at the scene and the area was cleared by police and cordoned off.

Amman, 20, was fresh out of prison. He was sentenced at London's Old Bailey court in December 2018 to three years and four months behind bars for terrorist offences and had been released early, standard procedure for good behavior, just a week ago.

In court, Amman had pleaded guilty to six charges of possessing documents containing terrorist information and seven of disseminating terrorist publications.

One of the manuals he admitted to owning was about knife fighting.

His attitude in prison was such that the authorities were concerned about his release and the risks he could present. As a result, he remained what the counter-terrorism police call a "subject of interest." That almost certainly accounts for the surveillance team that reacted so rapidly when he attacked the two people in Streatham.

Three people were taken to hospital, two of them believed to be victims of Amman's knife attack; a woman in her 50s and a man in his 40s. The man was initially described as suffering from life-threatening injuries but is now reported to be out of danger.

A third woman is thought to have been injured by glass fragments as a result of the police gunfire and has since been discharged from hospital.

Immediately after the incident, there was criticism of the sentencing rules that allowed Amman's early release from prison.

Usman Khan, the terrorist who killed two people in a sudden knife attack on London Bridge in November 2019 had also been released early from a prison sentence.

Following that attack, the Government announced tougher sentencing measures, enabling the authorities to extend incarceration. But these new rules would not have applied to Amman, because of the nature of his crimes.

Pressure is now certain to increase on the Home Office and Downing Street to revisit measures for extending prison sentences if the authorities are concerned about individuals.

But equally loud will be the calls for more effective deradicalization programs inside prisons, rather than simply extended incarcerations.