Police officers feared the Golders Green attacker may have had a bomb, Met chief Sir Mark Rowley has revealed.
He told how they became increasingly alarmed as the man resisted being detained.
Sir Mark spoke to the officers a few hours after the attack.
"You could still see they were shaken,” he told Times Radio on Friday.
"As that incident developed, they were afraid because he did not comply at all, even by being dropped to the floor by a Taser.
"They were afraid that he might have an explosive device on him from the way he was behaving.”
He told how the officers “used a lot of force” given the threat they felt they were facing.
The Scotland Yard boss told how he was "immensely proud" of how officers responded to the incident and their "most extraordinary” bravery.
"My officers were concerned that him having a big Puffa jacket and a rucksack he may have some explosives as well,” he told ITV’s Good Morning Britain.
"For them to be taking him on unarmed was absolutely remarkable."
Police tasered and arrested the suspect after the double stabbing which saw two Jewish men – Shloime Rand, 34, and Moshe Ben Baila, 76, named locally as Moshe Shine – taken to hospital.
Mr Rand told the BBC it was a “miracle” he survived, adding: “I feel like God’s given me back my life.”
He has been discharged from hospital and is now recovering at home after receiving stitches, Rabbi Levi Schapiro from the Jewish Community Council, who has visited both victims, said on social media.
Mr Shine remains in hospital and in a stable condition.
Commander Helen Flanagan, Head of Counter Terrorism Policing London, which is leading the investigation said: “Our thoughts remain with the victims involved and specialist officers continue to provide them with support as their recovery continues.
“We are determined to get justice for the victims and now that a person has been charged, I would urge everyone to avoid any further speculation in relation to this case so that justice can run its course.”
The Metropolitan Police said pro-Palestine marches across the country will be assessed after the UK terrorism threat level was raised to “severe” by the Joint Terrorism Analysis Centre on Thursday, meaning a terror attack is “highly likely”.
The decision is not solely a result of the Golders Green attack, the Home Office said, adding the threat level in the UK has been “rising for some time”.
The Stop the War Coalition is planning a major demonstration in London on May 16 to mark Nakba Day, commemorating the 1948 displacement of Palestinians during the creation of Israel.
The police chief said he was “disappointed”, adding the post was “inaccurate and misinformed”.
Earlier, Scotland Yard said a 45-year-old man has been charged with attempted murder after two Jewish men were stabbed in Golders Green,
Essa Suleiman, of Camberwell, south-east London, has been charged with two counts of attempted murder and one count of possession of a bladed article in a public place in relation to the attack in north London on Wednesday.
Suleiman is also charged with attempted murder in relation to a separate incident on the same date in Great Dover Street, Southwark.
He has been remanded in police custody and is due to appear at Westminster Magistrates’ Court on Friday.
Suleiman was born in Somalia and came to the UK legally as a child in the 1990s.
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