AFP has compiled what is known about the three men, amid an ongoing investigation into the third deadly jihadist assault.
AFP has compiled what is known about the three men, amid an ongoing investigation into the third deadly jihadist assault in Britain claimed by the Islamic State group in less than three months.
In at least two of the cases, the men were said to be known to police, raising pointed political questions just two days before a national election.
London police said Zaghba, 22, was an Italian national of Moroccan descent who had been living in the east of the capital.
Although British authorities said he was not known to police or security services, Italian officials said Britain was notified he was as a "possible suspect" back in March 2016.
Bologna prosecutor Giuseppe Amato said the warning had been passed on after Zaghba was intercepted at the city's airport trying to board a plane for Turkey, en route for Syria.
Italy's anti-terrorist force DIGOS believed he was trying to join Islamic State militants there.
He was detained carrying only a small backpack, his passport and a one-way ticket to Istanbul.
Police reportedly found IS propaganda videos on his cellphone, but after an investigation, they failed to find sufficient evidence of links to terrorism to justify prosecuting him.
Zaghba was the son of an Italian mother and a Moroccan father who had separated.
He had lived mainly in Morocco but had recently spent time working in Britain, most recently at a London restaurant, according to Italian media reports.
Zaghba was reportedly born in Fez, Morocco, in January 1995. His mother was said to have told police last year that he had asked her for money to travel to Rome before he left on his attempted trip to Syria.
Redouane was 30 and "claimed to be Moroccan and Libyan", national counter-terrorism police chief Mark Rowley said. Ireland's national broadcaster RTE reported that Redouane had an Irish residency card and had lived in Dublin.
Sky News said that Redouane, then using the name Rachid Elkhdar, had been denied asylum by Britain in 2009 but married a British citizen in Ireland in 2012.
Although they lived separately, he in Morocco, she in London, Redouane applied for an Irish visa in 2014 under rules covering marriage to an EU citizen, according to the report.
He received an EU residency permit from Ireland and the couple lived there until at least the end of 2015.
His last known residence was in Barking in suburban east London, where fellow attacker Khuram Shazad Butt also worked.
The Guardian reported that he worked as a pastry chef.
Butt, 27, was a British citizen born in Pakistan known to security services and even featured in a television documentary entitled "The Jihadis Next Door".
He was investigated in 2015 but he was "prioritised in the lower echelons of our investigative work" and there was no evidence of "attack planning", police said.
But his extremist views had reportedly prompted numerous people to go to the authorities.
They include a teenager who went to the same gym as Butt who said he was approached to join Islamic State, and a woman who told police she feared he was trying to radicalise children, The Times said.
Butt had sparked alarm for his extremist views and allegedly had links to a jailed radical preacher, yet neighbours in Barking remembered him as a friendly father of two.
His maternal uncle, Nasir Dar, told AFP in Pakistan that Butt's family moved to London when he was around four years old.
Butt returned to Pakistan in 2009 and 2013 on short trips, first for his brother's wedding and later to visit his own in-laws.
"He was a normal London guy just like other London party boys and started changing after his marriage. I don't know what was the reason behind this change but it came gradually," Dar said.
"We were happy that he was becoming more religious but did not know that in fact he was becoming a terrorist."
Butt had worked for the London Underground for six months last year as a trainee customer services assistant, Transport for London told the BBC.
British media said he had also worked at the fast food chain KFC and was an avid fan of the Arsenal football team.
His neighbours said he had been outgoing until they noticed an abrupt change in his personality.
"We saw him many, many times around here," said Salahudeen, a 40-year-old driving instructor.
"He used to be friendly but suddenly... he wasn't acting as normal. He wasn't aggressive; he used to chat but lately he was just 'hi' and 'bye'," he told AFP.
Michael Mimbo, 25, said the suspected attacker was nicknamed "Abz" at the local gym where he worked out regularly.