North Korea troops 'fire into South Korea'
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North and South Korean troops have exchanged fire across the border, South Korean officials say.
North Korea fired two rounds towards a frontline unit and South Korean soldiers returned fire three times.
The shooting occurred in Hwacheon, some 90km (56 miles) north-east of the South's capital, Seoul, according to reports from South Korea's YTN TV.
Officials say it was not clear if North Korea's initial shots were a deliberate provocation.
The border between the two Koreas is one of the most heavily fortified in the world, with many thousands of troops stationed on either side of a demilitarised zone.
