London: A second man was arrested over the terror attack on a London Tube train that left 30 people injured and resulted in an increase in the country's terror threat level from "severe" to "critical", police said on Sunday.
According to the Metropolitan Police, the 21-year-old man arrested in Hounslow, west London, on Saturday night, reports the BBC.
"He was arrested under the Terrorism Act and taken to a police station where he remains in custody," the Met police said.
Earlier on Saturday, an 18-year-old man was arrested the Port of Dover over the Friday morning attack, sending a ball of fire along a carriage of the eastbound District Line train from Wimbledon at the Parsons Green station.
Police are continuing to search a house in Sunbury-on-Thames in Surrey.
It is thought the 18-year old, who was arrested in the port of Dover on Saturday morning, lives there.
The BBC's home affairs correspondent Dominic Casciani, who is at the scene, said a large number of officers have been working inside the property and a forensics tent is in place in the back garden.
The house belongs to an elderly couple known for fostering hundreds of children, including refugees. Ronald Jones, 88, and Penelope Jones, 71 were rewarded for their service to children when they were made MBEs in 2010.
The couple are said to be staying with friends following the police raid, during which surrounding houses were evacuated. Friend Alison Griffiths said the couple had an 18-year-old and a 22-year-old staying with them recently.
She described Mr and Mrs Jones as "great pillars of the community", adding: "They do a job that not many people do."