The shelling of Yeonpyeong was an exchange of artillery between the North and South Korean military on Yeonpyeong Island on 23 November 2010. After a South Korean artillery practice on the island, North Korea fired about 170 shells at Yeonpyeong. The shelling damaged the island greatly. It killed four South Koreans and hurt 19. At this, South Korea shelled North Korean gun positions. North Koreans said that they had fired the shells because they heard South Korean shells being fired into the North Korean part of the sea. Many nations disapproved of what the North did, and the tension (angry feelings) in Korea grew. The United Nations said that it was one of the most serious things that had happened after the end of the Korean War.