More than 300 homes are being evacuated after an unexploded Second World War bomb was discovered near Falmouth Docks in Cornwall.
Police have established a 755-metre cordon around the area while a bomb disposal team assesses the device and determines the safest way to deal with it.
The bomb was found about 40 metres off Pendennis Headland on Monday morning. It is believed to weigh around 250kg and is thought to be an American air-dropped bomb dating from the Second World War.
The Royal Navy said mine clearance divers from Bravo Squadron were working to assess the unexploded device.
Residents living within the evacuation zone were instructed to leave their homes by 9am as emergency services carried out the operation.
Superintendent Vicky Howell of Devon and Cornwall Police said the cordon around Falmouth Docks had been extended overnight as a precaution.
She urged members of the public to stay away from the affected area and follow instructions given by police and other emergency services.
It remains unclear how long the evacuation will continue. Cornwall Council said residents affected by the operation can go to All Saints Church on Killigrew Street for support.
Train services between Falmouth Town and Falmouth Docks have also been suspended while the bomb disposal operation is under way.
The discovery comes after another wartime bomb was found at a building site in Plymouth in April. More than 1,000 homes were evacuated during that operation.
That incident occurred two years after another large-scale evacuation in Plymouth, which was triggered by the discovery of a 500kg German bomb.