NEW : Witnesses observe intermittent artillery fire from Turkey into Syria , CNN Turk reports . Syria says it is investigating source of gunfire fired into Turkey . No evidence of broader conflict , U.S. defense official says . Comment:
NEW : Witnesses observe intermittent artillery fire from Turkey into Syria , CNN Turk reports . Syria says it is investigating source of gunfire fired into Turkey . No evidence of broader conflict , U.S. defense official says . Turkey strikes targets in Syria following shelling of a Turkish border town .