 Complete the following phrase:  On 4 June 2010, four Chinese citizens were shot on suspicion of crossing the ChinaNorth Korea border for trade activities. Three died and one was injured. Qin Gang , spokesman for Ministry of Foreign Affairs publicized the news on 8 June. According to South Korean media reports, the people shot were members of a Dandong smuggling group on a ship on Yalu River. Cross-border smuggling is a common occurrence since North Korea is short on commodities supplies. The North Korean soldiers may have fired suspecting the Chinese citizens were South Korean spies after the South became more cautious due to the 