Berlin, Nov 4 (IANS/EFE): Bomb experts defused a 1,800-kg bomb from World War II Sunday in the western German city of Dortmund after officials evacuated 20,000 residents.

The specialists finished defusing the bomb in Dortmund's Hombruch district around 4:45 p.m. in an operation that lasted about five hours.

The only snag in the operation occurred around 3 p.m. when two wheelchair-bound people called police to say they had been unable to leave their residence and were still in the cordoned-off area.

Police and emergency services personnel evacuated people living within a 1.5-km radius of the bomb, which was found during an aerial survey of an industrial zone.

Unexploded bombs dating back to the intense air campaigns launched by the Allies against Nazi Germany are still found and defused periodically, but few of the bombs are as large as the one defused Sunday.

Only three 1,800-kg bombs have been found in Dortmund since the war ended in 1945.

The biggest evacuation in German history due to the discovery of a World War II bomb occurred in December 2011, when about 45,000 people had to be moved to safe locations so specialists could defuse a 1,800-kg bomb in the western city of Koblenz.