LONDON (AP) — A man who was apparently on the radar of British counterterrorism authorities strapped on a fake bomb and stabbed two people on a London street before before being shot to death by police Sunday in what they said was an Islamic terror attack.

One victim was hospitalized with life-threatening wounds, while the other suffered less-serious injuries in the rampage, which took place about 2 p.m. in the city's Streatham section, a combined residential and commercial neighborhood well removed from the world-famous landmarks of central London.

Officers responded quickly to the stabbings because of a "proactive counterterrorism operation" that was underway, Deputy Assistant Commissioner Lucy D'Orsi said without elaborating. Video from the scene appeared to show three undercover police officers in an unmarked car making a quick stop and emerging with weapons.

Bell Reberio-Addy, a member of Parliament who represents Streatham, said the attacker had been under surveillance "for some time."

D'Orsi said police believe the bloodshed was related to Islamic extremism. She gave no details and provided no immediate information on the assailant.

D'Orsi said there was no "continuing danger" to the public, but the area remained cordoned off as the investigation continued. The usually busy area was deserted as the public heeded police requests to stay away.

The drama about 5 miles (8 kilometers) south of central London marked a departure from recent terror attacks in the British capital that took place near landmarks such as London Bridge and the Houses of Parliament.

Prime Minister Boris Johnson said in the aftermath that the government would introduce "fundamental changes" to the way people convicted of terrorism offenses are treated. He cited Sunday's attack and another at Fishmonger's Hall in December as reasons for the changes.

The December attack was carried out by a man who had served time in prison for terrorism offenses. Johnson's reference to that case suggested something similar may have happened in this case.

The attack caused chaos and panic on what had been a typical Sunday afternoon, with the streets filled wish shoppers.

Karker Tahir said he was at work when he saw police chasing a man down Streatham High Road, the area's main shopping district.

"They kept telling him, 'Stop! Stop!″ Tahir said. "But he didn't stop, and then I saw that they shot him three times. It was horrible seeing it. The man was on the floor and it looked like he had something, which police said may be a device. Police came to us and said, 'You have to leave the shop because he has a bomb in his bag.'"

Images shared on social media showed a man lying on the sidewalk outside a pharmacy. D'Orsi said the device strapped to the assailant's body was quickly determined to be a hoax.

A third person suffered minor injuries, apparently from flying glass.

"The circumstances are being assessed,″ the Metropolitan Police tweeted. "The incident has been declared as terrorist-related."

Stephen Roberts, a former deputy commissioner for the Metropolitan Police, said if the stabbings were carried out by a "self-starter" — someone acting alone — it means any city in the country is vulnerable to a similar sort of low-tech attack.

The bloodshed took place a little over two months after two people were stabbed to death near London Bridge by a man who had recently been released from prison, where he was serving a 16-year sentence for plotting a terror attack.

In November, British authorities lowered the national terror threat level to "substantial,″ meaning an attack is considered likely. That is the third-highest rung in a five-step system used by British authorities and marked the first time since August 2014 that the threat level had been so low.

It was lowered because of the belief that the threat of British jihadis returning to the country from Syria had been reduced by events there, including the Islamic State group's loss of territory.

London Mayor Sadiq Khan urged community resolve in the face of another attack.

"Terrorists seek to divide us and to destroy our way of life,″ he said. "Here in London we will never let them succeed."

Also Sunday, police in Belgium shot a woman who stabbed and wounded passersby in the city of Ghent, but prosecutors said there was no suspicion of terrorism or a link to what happened in London.