A sand wall is being constructed around the bomb found in Great Yarmouth ahead of an explosion.
Carl Smith, leader of Great Yarmouth Borough Council, revealed he and other council figures visited some of the people evacuated from their homes last night.
The device is believed to date back to the Second World War and police have declared a major incident.
Several roads in the area have been cordoned off by police after the discovery at Bollard Quay, close to the junction with Boundary Road, shortly before 12pm on Tuesday.
Speaking to BBC Radio Norfolk, Mr Smith said: "The bomb disposal team are currently on site and they're currently building what's called a sand wall around the bomb for it to be exploded.
"About 400 tonnes of sand have been moved in overnight, I believe.
"They feel it's too dangerous to move it.
"It's right alongside the port on the river. There's houses on the left-hand side, there's also a garage which has got fuel tanks.
"There's also houses on the other side as well, so they were urged to evacuate their homes last night.
"The residents were fairly cheerful and were being looked after quite well."
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