About 200 people were temporarily evacuated from residences and offices at Tower Barracks in Grafenwoehr, Germany, upon the discovery of an unexploded 1,000-pound World War II bomb.

The bomb was found Thursday afternoon during prepping of a construction site for a new elementary school at Tower Barracks, Army Garrison Bavaria spokeswoman Susanne Bartsch told Army Times.

American and German unexploded ordnance personnel determined that about 10 housing units and several office buildings, including garrison headquarters, needed to be cleared before they defused the bomb. The evacuation started at about 2:30 p.m. and within an hour the area was clear and Gate 3 closed, Bartsch said. Experts began defusing the bomb at about 4 p.m., and people were cleared to return to the affected area at 4:38 p.m.

After removal, the bomb was taken to a range at the 105-year-old training facility, where it was detonated the same day.

Because Grafenwoehr Training Area was heavily bombed by U.S. forces in April 1945, undetonated explosives are still occasionally found. Sites must be cleared by explosive ordnance disposal personnel before construction begins.

Bartsch said personnel analyze old photos and visible craters to determine likely places a bomb might be found. They use metal detectors and other equipment to discover the buried relics before construction.