A stray grenade damaged a Russian post on the border with Ukraine Thursday, a day after the two countries agreed to begin talks this week on a long-term, mutual ceasefire, dpa reported. The blast, which occurred during fighting between Ukrainian government forces and pro-Russian separatists, shattered windows and caused other damage, officials in Rostov-on-Don told Russia's Interfax news agency. The damage followed the shelling of Russian border stations last week. Fighting has flared up in eastern Ukraine since Tuesday after the Ukraine government let a 10-day unilateral ceasefire expire.