Gunmen kidnapped three Irish members of the U.N. peacekeeping force in southern Lebanon Friday in the second such incident in less than 48 hours, police and U.N. sources said. Police said the three soldiers were abducted near a government hospital in the Shiite Moslem village of Tibnin, in Israel's self-declared security zone, 9 miles north of its border with Lebanon. Timor Goksel, spokesman for the U.N. Interim Force in Lebanon, said the three were abducted from a checkpoint they were manning in the village. "We were told by the people in the village that the kidnapping was in retaliation for the arrest by Israeli troops of four prominent Tibnin residents," Goksel said.