The Metropolitan Police said they were Khuram Shazad Butt and Rachid Redouane, both from Barking in east London.
Butt, 27, was a Pakistan-born British citizen while Redouane, 30, had claimed to be Moroccan and Libyan and also used the name Rachid Elkhdar.
The Met said: “Khuram Shazad Butt was known to the police and MI5. However, there was no intelligence to suggest that this attack was being planned and the investigation had been prioritised accordingly. The other named man, Rachid Redouane, was not known.
“Work is ongoing to understand more about them, their connections and whether they were assisted or supported by anyone else. We cannot say more about them at this stage.
“Detectives would like to hear from anyone who has any information about these men that may assist them with the investigation. They are particularly keen to hear about places they may have frequented and their movements in the days and hours before the attack.
“The investigation into this horrific attack is fast-moving and complex as we piece together a fuller picture of what occurred.
“So far officers have arrested 12 people — seven women and five men — and searched six properties, four on Sunday and a further two properties today. One of the arrested men and one of the women were subsequently released.”
The UK is facing a “severe and high tempo terrorist threat”, the force said.
The three attackers hired the white Renault van used to ram pedestrians on London Bridge, according to police.
Their assault, which began shortly after 10pm on Saturday night, left seven dead and dozens injured. Some 21 people are still fighting for their lives.
Michael Mimbo was a neighbour of attacker Khuram Butt, who he knew as Abz (Lizzie Dearden )
Butt was known to his friends as “Abz”, and neighbours described him as a doting father-of-two and an Arsenal fan. They said he was friendly and polite, saying the he was known for attending barbecues, playing with local children and giving out sweets in the nearby park.
But in recent months some parents had raised concerns about “brainwashing” after their children came home saying they wanted to become Muslims.
Abz had appeared in a 2016 Channel 4 documentary about British jihadis, in which he was seen among a group of extremist praying with a black Islamist flag in Regent’s Park in central London.
A former friend told the BBC’s Asian Network he had contacted the authorities after becoming concerned about Butt’s extremist views.
Butt had been radicalised watching extremist videos online, he said, adding: “We spoke about a particular attack that happened and like most radicals he had a justification for anything and everything, and that day I realised I needed to contact the authorities.”
Michael Mimbo, who lives across the road from the man he knew as Abz, told The Independent his neighbour never spoke to him about religion and politics, mainly sticking to their shared passion for Arsenal or passing the time of day at a nearby gym.
But he recalled him appearing increasingly devout in recent months, growing his beard longer and starting to regularly wear traditional Islamic dress.
“Football was his thing – when I saw that picture of him [shot on the ground] I recognised his shirt,” said Mr Mimbo. “I thought maybe he was just devoting himself a bit more and becoming more religious.
“But I never, ever would have expected this – we didn’t have a clue that he was capable of this.”
A woman who gave her name as Ramona Huczko remembered Abz doting on his young son and new baby.
“He was a good father,” she told The Independent. “You’d always see him feeding his son. We’re shocked that he could do this – he is the devil.”
After further arrests were made in Caledon Road, East Ham, one 22-year-old neighbour who did not want to be named told The Independent: “It sounded like an explosion”.
They addded: “Then we heard bang, bang, bang, bang – it was frightening.”
Ben Tamaklo, who lives on the residential street, said he looked out to see armed police swarming the street.
This report was originally published inIndependent and Click for more.