Over 20 people, including foreigners, were still missing after a tug boat sank in the Yangtze river in China's Jiangsu province, authorities said Friday.There were seven or eight foreigh technicians on the boat, including Singaporean and Japanese nationals, who were among the missing. A French citizen may also be among those missing, Xinhua reported. The boat was on a trial voyage Thursday afternoon when the accident happened.So far, three people have been saved and the search and rescue mission is still underway.