At least five sailors remain missing after a Chinese fishing boat collided with a South Korean cargo ship and sank off South Korea's southern coast early Saturday, South Korea's Coast Guard told Xinhua. There were at least 7 sailors on the boat when it collided with South Korea's 6,049-ton cargo ship "Bright Ace" at about 8:40 a.m. Saturday (2340 GMT Friday) on waters about 370 km south of South Korea's southern most island of Mara, said Kim Hyung-wook, a police officer of the Coast Guard's Jeju Bureau. Two sailors of the fishing boat have been rescued by the South Korean cargo ship so far, Kim told Xinhua through telephone. The Coast Guard has dispatched a vessel from Jeju island to the scene, Kim said, adding the vessel is expected to reach the spot at about 9 p.m. (1200 GMT) Saturday due to the distance. About 3-4 Chinese fishing boats gathered near the spot of the accident for assistance, Kim said. The cause of the accident is still unknown, he added. The cargo ship carrying 6,000 tons of steel materials was heading for Singapore after leaving Masan port Thursday night, local media reported.