Up to 1,000 homes in Plymouth are being evacuated after the discovery of an unexploded bomb.
Experts will start examining the bomb when the 100m zone is clear
The device was found by workers on a building site in Brentor Road, in the Prince Rock area of the city.
It is sticking about six inches (15cm) out of the ground and is 10ins (25cm) in diameter.
Bomb disposal experts have confirmed it weighs about 250lb (113kg). It is thought the device will be removed from the site and detonated at sea.
Specialist equipment has been sent to Plymouth from Wales and when the bomb is moved, buildings on the route may also have to be evacuated.
"Evacuations are being carried out of properties within 100m [328ft] of the scene," a police spokesman said.
"Properties within the 100m-300m [328-984ft] zone are being advised to open windows and draw curtains."
Some people unable to get into their homes when they returned from work have said they are worried about their pets.
Plymouth City Council's emergency planning officer is at the scene and the council has taken residents with no alternative accommodation to Stoke Damerel Community College.
The Explosive Ordnance Disposal (EOD) team will not begin to examine the bomb until the 100m zone has been fully cleared.
The operation is expected to last for several hours.