German police in the northern city of Bremen say they have evacuated more than 100 homes and apartments to carry out the controlled-detonation of a 500-pound World War II-era bomb.

The American bomb was found earlier Wednesday during construction in the area.

The evacuations were carried out in a 300-yard radius of the bomb, though police warned residents in the immediate area beyond that to keep their windows closed and duck or lie down during the controlled explosion.

Though World War II ended more than six decades ago, it is still relatively common for unexploded Allied bombs to be found in Germany.