Government troops killed 10 U.S.-backed Contras after the rebels attacked a village in northern Nicaragua and attempted to kidnap a group of civilians, state-run media said. The Voice of Nicaragua radio said some of the rebels escaped, taking with them four civilians from the village of San Juan del Rio Coco, about 80 miles north of the capital of Managua. The radio said that government troops also captured military supplies from the Contras. It did not mention Contra wounded or any Sandinista casualties. State-run television said the rebels’ bodies will be put on public display today.