LONDON (AP) — An unexploded World War II bomb will be transported Friday through the southwestern English port city of Plymouth by a military convoy and disposed of at sea, prompting one of the largest evacuations in the United Kingdom since the war.

Devon and Cornwall Police said the bomb, which was found in a residential yard on Tuesday, will be taken to the Torpoint Ferry slipway to be disposed of at sea beyond the breakwater. The bomb is believed to weigh around 500 kilograms (1,100 pounds), according to the U.K. Ministry of Defence.

More than 3,000 people have been evacuated from their homes, and those living in the vicinity of the route being taken by the convoy should leave their homes too. The journey is expected to take around 20 minutes. The Ministry of Defence said that the evacuation is one of the biggest since World War II.

The decision to move the bomb was taken after an assessment by bomb disposal experts concluded that there would be too high a risk of significant damage, including the destruction of a number of houses, if the device were detonated in the yard.

“That's the least impactful option,” police Superintendent Phil Williams said. “There's obviously an element of risk and it's been assessed by the army and deemed this is the lowest risk.”

The hope is that those affected by the cordon should be able to return home by 5 p.m. on Friday.

The main train line into the city will be closed as it travels through the cordon, while ferries will be suspended and buses will be diverted. Schools and nurseries have also closed to allow the operation to take place, while all businesses within the cordon have been told to evacuate.

Plymouth, a major naval city in the United Kingdom, was targeted by Germany during World War II. An estimated 10% of German bombs that were dropped during the war didn't explode, leaving many towns and cities in the U.K. littered with unexploded ordnance.