GUANGZHOU, Dec. 27-- The Zhanjiang City maritime search and rescue department believes it has located five missing crew members, who were left adrift after their boat sank off the coast of south China's Guangdong Province Friday evening.

The Zhanjiang maritime safety agency had previously announced that seven crew members were onboard the boat at the time of the incident but later revised this number to six.

The agency said five were on a life raft, which it was tracking by the triangulation of cellphone signals. One person remains unaccounted for.

Three helicopters have been despatched to locate the raft, the agency said.

The Hongxiang 538 pinged a rescue signal to a nearby boat and before they lost signal, the crew said they were about to take the life raft, according to the safety agency.