South Ossetia claims it's under fire from Georgia
Sunday's incident follows a deadly attack on Friday, when the self-proclaimed republic's capital and nearby villages came under heavy artillery fire.
One person died and three others were wounded during the shelling.
South Ossetia and Georgia have blamed each other for starting the violence.
Tensions are not uncommon between Georgia and its breakaway republic of South Ossetia.
The region declared independence from Tbilisi in the early 1990s and a violent conflict ensued.
Since then, peacekeepers from a joint control commission have been stationed in the region.
To date, the breakaway republic hasn't been recognised internationally.