FRANKFURT, Oct. 23 — More than six decades after the end of World War II, Germans still routinely come across unexploded bombs beneath farmers’ fields or city streets. Lately, there has been a skein of such dangerous discoveries, one with deadly consequences.

On Monday morning, a highway worker was killed when his cutting machine struck a World War II bomb beneath a busy autobahn southeast of Frankfurt. The explosion ripped apart the vehicle and damaged several passing cars, wounding four other workers and a motorist.

Also on Monday, a weapons-removal squad defused a 500-pound bomb found next to a highway near Hanover, in the north. The police said it was a British aerial bomb, one of tens of thousands dropped on German roads, factories and cities during Allied bombing raids.

Allied warplanes dropped about two million tons of explosives on Germany, ranging from small firebombs to giant high-explosive bombs. There are also buried mortars, land mines and hand grenades, which often turn up during road construction or other major excavations.