An unexpected heavy fog caused a pileup on an expressway in central China's Hunan Province, killing at least four people Saturday, local authorities said.

More than 30 vehicles were involved in the accident, which occurred at about 7 a.m. on the Beijing-Zhuhai expressway near Zhuzhou City, a spokesman for the Hunan Provincial Expressway Administration said.

The expressway traffic was halted for about five hours after the accident, he said.

But he said that he was unclear about whether there were people injured in the accident.

A traffic police officer reached via mobile phone at the pileup site told Xinhua that an investigation was underway.

But he would not provide further details.

(Xinhua News Agency November 11, 2007)