Three US citizens, seized by Nicaraguan forces while cruising along a river in motorboats, were freed, a Costa Rican minister said. Harry Kime, David Donaldson, and Luke Dallis arrived here from the frontier after they were detained by Nicaraguan forces on Friday. They said they were cruising on a river inlet 12 miles inside Costa Rica when they were arrested. Nicaragua contended they were boating on an ill-defined stretch of the San Juan river. Nicaraguan leader Daniel Ortega and Costa Rican President Luis Alberto Monge plan to meet in May to reduce border tensions.