A teenager is in custody and the home of a respected foster couple has been raided as part of the investigation into the Parsons Green Tube bombing.

Police are searching a house in Sunbury-on-Thames, Surrey, after an 18-year-old - understood to be the suspected bomber - was arrested in Dover earlier on Saturday.

Residents in the Cavendish Road area of Sunbury-on-Thames, Surrey, evacuated by police at 1.40pm.

The property is registered to foster carers Penelope, 71, and Ronald Jones, 88, who were awarded MBEs in the 2009 New Year's Honours List for services to children and families.

Several residents said the couple lived there and Nicola Ryder, who lives opposite, described the couple as "beautiful people".

She said she knew them just as Penny and Ron, and that they would foster up to seven young people at a time between the ages of 10 and 18.

The couple featured in an interview with Elmbridge CAN, a community group which aims "to build a culture of welcome to refugees" and help settle them in the local community.

The organisation states that Mr and Mrs Jones have been foster parents for almost 40 years and had taken in 268 children - the last eight of which were refugees. It is not clear when the interview was published.

In the interview Mrs Jones said fostering "had its ups and downs", adding: "They're all children, it doesn't matter if they're sky blue or with pink dots on them - they just need to be loved."

Police established a 100m exclusion zone around the Jones's address and nearby residents were evacuated as a precautionary measure.

Earlier the 18-year-old was detained on suspicion of preparing a terrorist act, sparking an evacuation of the ferry terminal, Deputy Assistant Commissioner Neil Basu said.

Detectives investigating the bombing were said to be "keeping an open mind" about whether more plotters were involved and Mr Basu said the terror threat would remain at its highest level, indicating another attack was feared.

The suspect is now being held at a London police station after being arrested by Kent Police.

Residents across Sunbury spoke of how they were forced to flee their homes following the arrest.

Mojgan Jamali, who lives in Cavendish Road, said she was told by police she had "one minute" to pack her bags, grab her children, and leave her home as police carried out urgent evacuations.

"I was in my house with my children and there was a knock at the door from the police," the mother-of-three said.

"They told me to leave. They said: 'You have one minute to get out of the house and get away.'

"I just got out, I got my three children and we left the house and the street.

The Dover arrest came just over 24 hours after an improvised explosive device injured 30 people as they travelled during the Friday morning rush-hour.

The attack, which was since been claimed by so-called Islamic State, led to the UK terror threat led being raised to critical - the highest level. Scotland Yard described the arrest as "significant" but warned that the investigation "continues".

Highlighting an increased visible police presence after the Parsons Green bombing, Metropolitan Police Commissioner Cressida Dick today said: "London has not stopped after other terrible attacks and it will not stop after this one."

Scotland Yard said 45 witnesses had been spoken to and 77 images and videos sent to detectives by members of the public.

Parsons Green was shut down on Friday morning after the improvised explosive device sent a fireball through a carriage on a packed District Line train.

The package, wrapped in a supermarket bag, appeared to have been left on the train where it caught fire.

Nineteen of the victims were taken to hospital by ambulance, while a further 11 presented themselves - many suffering from burns.

Three still remain in hospital care, the NHS said.

Having been shut for the remainder of Friday, Parsons Green was re-opened to the public in the early hours of Saturday.

Announcing the raised threat level, Mrs May said police had asked for authorisation to enact part of the first phase of Operation Temperer - "a well-established plan to provide military support to the police".

The use of the military is believed to allow up to 5,000 troops to be deployed in support of the police.

The plan was activated for the first time on May 23 following the Manchester Arena bombing.