Overnight fighting that included sniper and mortar fire between Georgian forces and separatists in the breakaway South Ossetia region left six people dead and 13 wounded, regional officials said Saturday. The fighting _ from Friday evening and through Saturday morning _ was one of the most serious outbursts in the tensions that have plagued South Ossetia since it split off from Georgia after fighting in the mid-1990s, the Associated Press reported. Georgia says it opened fire in response to South Ossetian attacks on several villages that left five civilians and a police officer injured. South Ossetia government spokeswoman Irina Gagloyeva said six people were killed and 13 wounded in the fighting, but she did not say which side they were on or specify if they were civilians, troops or law enforcement. Gagloyeva told The Associated Press that Georgian forces started the fighting around 6 p.m. Friday with snipers firing on the northern portion of the republic's capital, Tskhinvali, and on several of its forces' posts. The firing lasted about three hours, then paused and resumed with mortar fire that lasted until about 8 a.m. (0400 GMT), she said. Georgian Interior Ministry spokesman Shota Utiashvili said South Ossetian forces began the clash by firing on at least three villages in Georgia-controlled territory.