NANNING - Five people were killed, one was injured and one escaped in an expressway tunnel collapse early Wednesday in south China's Guangxi Zhuang Autonomous Region, sources with the rescue command center said.

The accident occurred around 4 a.m. at the section of Najia Township, Debao County, along the expressway between Baise City and Jingxi County, which was under construction.

A total of seven people were working within the tunnel when the accident occurred. One escaped and six others were buried, including five who died and one who was injured, said Xie Deqiang, Communist Party chief of Debao County.

The injured has been sent to a nearby hospital, according to the sources.

An investigation into the cause of the accident is under way.