Hundreds of families are spending the night in a school hall as army disposal experts work to defuse an unexploded Second World War bomb.
The bomb was discovered by contractors at a building site in east London at around 12.45pm on Monday, leading to the introduction of a police hazard zone and the initial evacuation of 150 people from houses and business.
Ministry of Defence (MoD) experts arrived at Temple Street, Bethnal Green, at around 5pm to defuse the 500lb device and are expected to be working through the night.
The hazard zone has been extended to 200 metres, meaning more families are being evacuated to a Bethnal Green Academy where Tower Hamlets Council has set up a rest centre.
A council spokesman said: "After discussions with the Army, the London Fire Brigade, and the Metropolitan Police, we have agreed to extend to exclusion zone to 200 metres. The operation is likely to last throughout the night.
"We understand that this will cause inconvenience for a lot of residents. We urge residents to look at alternative places to stay for the night. We do have an operating rest centre at the Bethnal Green Academy - where we will be providing beds, food, drinks, and wash bags."
An MoD spokesman said: "A specialist military bomb disposal team from 11 EOD Regiment, Royal Logistics Corps are on site in Bethnal Green and are assisting the police with the ongoing incident involving a World War Two German aircraft bomb."
Earlier this year the squadron defused similar historic bombs in Bermondsey and Wembley.
Several roads remain closed as police warned of "significant traffic disruption" and Transport for London (TfL) said there was no impact to Tube or overground services, but four bus routes were being diverted.
London Fire Brigade group manager Pat Goulbourne said disruption could last until the early morning.
"It is likely that this incident will continue throughout the night and there is the potential for disruption early tomorrow morning. We'd advise that people avoid the area during tomorrow's rush hour and use alternative routes," he said.
Police have advised motorists to avoid several roads including: Old Bethnal Green Road, Warner Place, Squarres Street, Bethnal Green Road, Cambridge Heath Road and Hackney Road.