Police in London are focused on a very unlikely location for a suspected bomb factory in the London suburb of Sunbury-on-Thames in connection with the subway attack that sent at least 30 people to the hospital on Friday morning.
An 18-year-old man and a 21-year-old were arrested separately by police on Saturday, a day after the incident, according to United Kingdom police.
"For strong investigative reasons, we will not give any more details on the man we arrested at this stage", Deputy Assistant Police Commissioner Neil Basu said earlier.
An 18-year-old man was also detained in the departure area of Dover ferry port on Saturday morning.
Detectives from the Met's Counter Terrorism Command are continuing to urge anyone with information about the terrorist attack to contact police.
"A significant amount of activity has taken place since the attack on Friday", Haydon said.
Police said Thursday that terrorism-related arrests had risen 68 percent over the past year.
Police announced Tuesday the arrest of a 25-year-old man in Wales.
"A search is taking place at an address in the Newport following the arrest".
West Thames College in West London said in a statement that "Yahyah Farroukh, who, according to media reports is the second suspect detained in connection with the Parsons Green incident, was a former student at the college from December 2013 to June 2015".
The two arrests indicate police and security services believe the attack was part of a coordinated plot, not the act of a single person.
Farroukh was arrested after he finished his shift at a fried chicken shop in Hounslow, west London.
An unnamed witness came forward to say: "The guy had just walked past the takeaway when three blokes and a woman came running past and he was rugby-tackled to the floor".
He added: "As police and our partners do all we can to confront the threat, public vigilance remains as vital as ever".
A local politician said he understood an 18-year-old Iraqi orphan was living with the couple, having moved to Britain at 15 after his parents died.
The video shows a figure dressed in grey carrying a white Lidl carrier bag around 80 minutes before the explosion that injured 29 people.
The detonation, considered by police to have been partial, was claimed by Islamic State.
He says the 21-year-old was also a former foster child of the Joneses.
Mr Harvey, who leads Spelthorne Borough Council, told the Press Association it was "widely known" the 21-year-old was a former foster child who had lived at the property being searched in his ward of Sunbury East.