Rescuers are searching for seven crew members who went missing after their cargo ship sank on Sunday off the coast of Yantai City in China's Shandong province, which killed four people, authorities said.According to the Beihai Rescue Bureau of the Ministry of Transport, a total of 14 crew members were on board when the accident occurred, reports Xinhua news agency.The rescue bureau received a report of the accident at 4.43 a.m.So far, three people have been rescued.A rescue helicopter and a rescue vessel have been dispatched to search for the missing crew members.