(CNN) -- Turkey fired on Syrian government targets in response to the shelling of a Turkish border town in which five civilians were killed Wednesday, according to Prime Minister Recep Tayyip Erdogan's office. The town of Akcakale "was hit by artillery fire belonging to the Syrian regime forces," a statement from Erdogan's office said, in the first clear assertion of blame for the shelling. "Our armed forces on the border responded immediately to this atrocious attack within the rules of engagement, and points in Syria determined by radar were hit with artillery fire," it said. "Turkey, within the confines of the rules of engagement and international law, will never leave these types of provocations aimed at our national security unanswered."
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NEW: Witnesses observe intermittent artillery fire from Turkey into Syria, CNN Turk reports
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Syria says it is investigating source of gunfire fired into Turkey
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No evidence of broader conflict, U.S. defense official says
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Turkey strikes targets in Syria following shelling of a Turkish border town
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