A shell or grenade buried in western Belgium since World War One, has exploded, killing two people.
At least two more were injured, one of whom is in critical condition.
The device was set off as workmen at a building site in Ypres were trying to dig it up.
A strategic city, Ypres was shelled by German forces for most of the war and unexploded weapons are often found there.
The area, where a factory is being built, has been sealed off and local explosives experts have been brought in.
It is thought that thousands of explosives from the 1914-1918 war still lie buried in and around Ypres, yet to be discovered.
Every year the former battlefields of western Belgium throw up hundreds of Great War armaments. Most are destroyed without incident by a special Belgian army bomb squad.
Despite that, several hundred people have been killed in similar explosions since the end of the war.
The Flanders battlefields cover dozens of cities where Allied forces clashed with their Germany enemies for most of the war.