One body of the 20 victims killed in the?Hunan Province?tunnel explosion Saturday has been retrieved, rescuers?said in the wee hours of Sunday, Xinhua reported. [Photos]

When the blast occurred, a total of 24 people were working in the Bamianshan tunnel, which is being built for the Yanling-Rucheng expressway, in Yanling county of Zhuzhou city.

Four of them were pulled out, including one in critical conditions and another slightly injured. The two injured have been hospitalized.

Rescuers have conducted life detections six times at the site, with no sign of life detected.

The explosion happened at about 8:30 a.m. when a vehicle carrying explosives was unloading in the tunnel that involves a designed length of 2,355 meters.

The explosives were contained in 12 cases, each weighing 24 kilograms. An investigation into the cause of the explosion is under way, and rescue and clear-up work is continuing.