A loud explosion and a mystery crater that appeared overnight near a German town was likely caused by a World War II bomb that detonated decades later, authorities say.

The 33-feet wide and 13-feet deep crater was discovered Sunday in a field near Limburg, police say. Residents reportedly heard and felt a loud blast early Sunday, but no injuries were reported.

Police said Monday that there was no indication farm equipment or other machinery caused the crater.

Bomb-disposal experts said "with almost absolute certainty" that a WWII bomb was to blame for the crater and that they believe it was dropped by a plane at the time, the BBC reported.

Limburg's spokesman Johannes Laubach told Hessenschau that the city was a common bomb target as the war was ending.

"We can be glad that the farmer was not in the field," he added, according to a translation.

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Finding undetonated WWII bombs is not uncommon in Germany. According to CNN, several have been defused in recent years in major cities like Berlin and Frankfurt.

Stunning drone photos showed the extent of the damage the suspected bomb caused.

Contributing: The Associated Press. Follow USA TODAY's Ryan Miller on Twitter @RyanW_Miller