NAIROBI, Kenya — South Korean snipers hovering in a helicopter Monday chased away pirates pursuing a North Korean freighter, while a Russian warship freed eight Iranian citizens held hostage for more than three months. The two dramatic rescues in the Gulf of Aden come as piracy grips the lawless coast off Somalia. South Korea's Joint Chiefs of Staff said in a statement that the 4,500-ton-class warship sent a Lynx helicopter to assist the North Korean vessel shortly after receiving a distress call that it was being chased by the pirate ship. The pirate vessel gave up chasing the North Korean vessel and sped away after snipers aboard the helicopter prepared to fire warning shots, the statement said. The incident took place 23 miles (37 kilometers) south of the Yemeni port of Aden, according to the Joint Chiefs of Staff.