Jakarta, Aug 28 : A cargo ship with 15 people on board sank in the Makassar Strait of central Indonesia, leaving 11 people missing, an official said on Saturday. The ship was hit by huge waves while sailing in the waters between Kalimantan island and Sulawesi island on Monday but the accident was found out by a passenger ship which helped the victims on Friday, senior press official at South Kalimantan's search and rescue office Dendy Prasetyo was quoted as saying by Xinhua news agency. "Today (Saturday) we carried out a search and rescue operation to look for the 11 missing persons," he told the news agency over phone. Four people survived the accident, as they used a lifeboat and were helped by a ferry, said Prasetyo. The cargo ship loaded with cement departed from a seaport in South Kalimantan province and was heading to a seaport in South Sulawesi province, according to the official. /IANS