A letter bomb exploded at an office for regional officials in the Bavarian town of Regen on Monday. One woman sustained slight injuries from the bomb which was addressed to district administrator Heinz Wölfl, a Christian Socialist Union member, police said. A second letter bomb was sent to Reinhold Perlak, the Social Democratic mayor of the nearby Bavarian town Straubing. The bomb was discovered before it could explode, the Bavarian authorities reported. Four other letter bombs have been sent to politicians in Bavaria since spring, though none of them have detonated.