A major airport in northern Japan has been closed after an unexploded bomb believed to be from World War II was found.

Local police official Hiroshi Ouchi said flights in and out of Sendai airport were cancelled Tuesday after the 550-pound bomb was uncovered during construction near a runway. It was identified as American-made and is believed to be a dud from World War II.

Ouchi said a military bomb squad was called and evacuations were being considered.

Japanese cities were bombed heavily during World War II, and finding duds is not unusual. The rusty condition of the bombs can make them prone to detonate when moved, but injuries are rare.

The Sendai airport was closed for months due to damage from last year's tsunami.