SEOUL, South Korea (AP) — South Korea on Monday returned fire into North Korean waters after shells from a North Korean live-fire drill fell south of the rivals’ disputed western sea boundary, a South Korean military official said. Residents on a front-line South Korean island said they were evacuated to shelters during the exchange.

No shells from either side were fired at any land or military installations, an official with South Korea’s Joint Chiefs of Staff said. He provided no other details and spoke on condition of anonymity because of office rules.