About 5,400 residents were evacuated in Osaka in western Japan and flights at nearby airports were rerouted Sunday as army experts disposed of a large unexploded bomb believed to have been dropped by the U.S. military during World War II, authorities said.

An explosives disposal unit from Japan's Ground Self-Defense Force safely defused the rusty one-ton bomb in the crowded residential area during a 50-minute operation, local army spokesman Shoji Matsumoto said.

Nearby highways and roads were closed, and city buses, boats and flights in and out of nearby airports were rerouted, city officials said in a statement.

The bomb — about 6 feet long — was found by workers at a construction site last month, Matsumoto said.

Although the war ended more than 60 years ago, unexploded bombs still turn up regularly in Japan, where U.S. forces conducted extensive air raids against major cities.

A similar bomb was found in the outskirts of Tokyo in May, forcing 16,000 residents to evacuate for a disposal operation. Another one was unearthed in Osaka three years ago.