More than 150 people have been evacuated from homes and offices in Bethnal Green in East London, and many have found refuge at a nearby school set up by authorities.
"We can confirm that a specialist military bomb disposal team from 11 EODRegiment, Royal Logistics Corps are on site," an Army official said in a written statement.
"Residents stayed the night at Bethnal Green Academy, where they were put up on camper beds and fed," Tower Hamlet Council said in a written statement. "We’d like to thank everybody for their patience and understanding around this, and we’ll continue to update residents as and when we get more information."
One veteran, Harry Leslie Smith, who used to be in the Royal Air Force, took to Twitter, saying "70 years on and World War Two is the conflict that still can't stop giving."
Alex Georgiou, who was working in the neighborhood, told ABC News he had been evacuated but the area was coordinated so far back that it didn't really affect him.
Another evacuee, Rachel Walker, said police initially told her she was far enough to be unaffected by any potential blast, but was eventually told to leave. Walker was able to work in the lobby of a nearby hotel and stayed the night with friends.
"It's a stark reminder of the history of the area, and humbling really to think of what East Enders had to deal with on a daily basis during The Blitz," Walker said.
Similar bombs were discovered in two areas of London, Wembley and Bermondsey, earlier this year.