Video: World War II bomb explodes unexpectedly in UK

Security forces confirmed that no injuries were reported. The detonation occurred when workers were trying to deactivate it.

The detonation of a World War II bomb set off a huge - unplanned - explosion that could be heard several miles away in the town of Great Yarmouth, England.

Norfolk County Police reported that the device was discovered Tuesday by one of the builders erecting a bridge in that area (over the Yare River). The unexpected detonation occurred when workers were trying to deactivate it. Norfolk Assistant Chief Constable Nick Davison detailed:

It was not a planned detonation. It exploded shortly after work began to dismantle it.

Security forces reported that no injuries were reported and all members of the Army and emergency services on the scene are "accounted for":

Fortunately, all personnel are accounted for and agencies are beginning to assess the damage to the river wall.

An"unintentional" detonation

Before workers began handling the object - 3.2 feet long (1 meter) and weighing 551.1 pounds (250 kilograms) - a protective wall was erected with sand as a safety measure. "Our strategy was the safest option. However, there is always the risk of an inadvertent detonation," Davison added.

On its Twitter account, Norfolk Police detailed how, "an unexploded bomb in Great Yarmouth detonated earlier during work to defuse it. Our drone captured the moment. We can confirm that no one was injured. Public safety has been at the center of our decision making throughout this operation, which we know has been a long one."

Army specialists had been attempting to defuse the bomb since last Thursday using a "technique that creates a slow combustion of the explosives". Davison noted in a statement:

This was the final phase of a delicate operation that has caused much disruption in the city, it has been a painstakingly long process, but public safety and the safety of the people involved in the operation has been at the heart of the decision making.

A spokesman for Cadent - the company that manages the local gas distribution network - said the company conducted a "thorough inspection of our pipelines in the surrounding area."

There is no indication that the explosion caused damage to our assets and gas continues to flow safely.