A bulldozer driver was killed and 13 others were injured in a western German town Friday after a World War II bomb or mine exploded, police said.

The explosion happened in an industrial area of Euskirchen, near Bonn, at a property used by a construction firm to sort and dispose of rubble. It wasn't immediately clear whether the explosives had long been buried in the ground or had inadvertently been brought to the site in a delivery of demolition waste.

The bulldozer driver was fatally injured after his vehicle hit the device and two people who were close by suffered serious injuries. Another 11 people who were in the area were lightly injured.

Windows, roofs and doors as far as 400 yards away were damaged in the blast, police said. Explosives experts were working to determine exactly what the device was.

Unexploded World War II-era bombs are still discovered frequently in Germany, though it is rare for those finds to result in death or injury.

An estimated 200 million pounds of unexploded and potentially dangers explosives -- from bombs to missiles to mustard gas -- lurk, and leak, beneath the world's oceans.

In 2012, Texas A&M oceanographers William Bryant and Niall Slowey conservatively guessed that at least 31 million pounds of bombs can be found not just in the Gulf of Mexico, but also off the coasts of at least 16 states, from New Jersey to Hawaii.

Sea disposal of munitions was an accepted international practice until quite recently. Dumping conventional and chemical munitions captured from enemies -- from Nazi Germany, for example -- was also an accepted practice.

Fox News' Allison Barrie and The Associated Press contributed to this report.