Two 250-kilogram (550-pound) bombs were safely defused in Dortmund's southwest on Sunday following a large-scale evacuation and the closure of the city's main train station.

The city administration said earlier that special disposal teams had discovered four suspected bombs from World War II in the densely populated Klinikviertel (clinic quarter). But substrata searches of the area confirmed that two of the objects were not explosives.

The other two devices — an American bomb and a British bomb — were successfully detonated on Sunday afternoon.

Containers stacked as walls blocked streets to absorb potential blast waves, and barriers warned that "entry is forbidden," as the operation got underway. Police helicopters scanned the streets from overhead to ensure residents had left as instructed.

Read more: Evacuations as Dortmund scans for suspected WWII bombs

Containers stacked across a Dortmund inner-city street to absorb potential blast waves

A total of 14,000 people were asked to leave their homes. Starting Saturday, hundreds of patients and senior citizens had been relocated from two hospitals in the area. Several hundred residents unable to stay with relatives and friends had headed to an outlying school converted into a social center by Sunday morning. They were given the all-clear shortly after the bomb disposal was completed.

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A bomber from Britain's Royal Air Force flies over Germany's Ruhr region during a raid on October 12, 1944

Adjacent main rail station closed

Dortmund's famed Football Museum and its main railway station were closed to through traffic from midday. Substitute passenger buses were provided to two other Ruhr District rail hubs, Duisburg and Wanne-Eickel near Herne.

Dortmund Zoo's offer of free entry to those evacuated had been taken up by 300 residents, reported public broadcaster WDR Sunday.

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Ruhr District pummeled in 1943

The bombs stem from World War II. British squadrons bombed central Dortmund heavily in May 1943 during a monthslong Allied aerial campaign to pummel heavy industry in the surrounding Ruhr District used by the Nazi regime at the time.

Defusing unexploded ordnance is still a frequent exercise across Germany, because an estimated 10% penetrated the ground and failed to detonate. In the past, similar evacuations have included Koblenz, Augsburg, Dresden and Frankfurt.

Construction projects — as are planned for Dortmund's precinct — are typically preceded in Germany by checks for unexploded ordnance, often using old Allied aerial photos showing impact craters left during the World War II.

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nm,ipj/rc (dpa, AFP)