(CNN) -- The Japanese Coast Guard on Thursday rescued four survivors after a Chinese cargo ship went missing, officials and state media said. One of the four was in critical condition.
The cargo ship went missing early Wednesday south of Iriomote Island in Japan's Okinawa Prefecture, an official from the Chinese embassy in Japan said Thursday, according to Chinese state media.
The remaining 21 crew members and the Panama-registered ship had not been found, China's Xinhua news agency said, citing Jin Mingyu, consulate of the Chinese embassy in Tokyo.
The Japanese Coast Guard found the four survivors, as well as a crew mate who had already died, guard spokesman Daisuke Hirasawa said. They were all wearing life jackets and were drifting. The Coast Guard also found two empty life boats.
A 26-year-old rescued seaman said water suddenly entered the cargo ship's engine room, so he jumped into the sea after putting on a life jacket, the Japanese Coast Guard said.
The rescued crew members were being sent to Ishigaki in Okinawa for treatment, Jin said, according to Xinhua.
"Japan's Coast Guard are exerting every effort to search for the missing, and officials from the Chinese consulate in Fukuoka will arrange a visit to Ishigaki to deal with related issues," Jin added.
The cargo ship last made contact about 7 p.m. Tuesday, Xinhua said.
CNN's Chie Kobayashi contributed to this report.