CHANGSHA - A rock hit an expressway construction site in central China on Monday, leaving four workers dead, local officials said.

The accident occurred in the early morning in the county of Xupu in Henan province, when a huge rock weighing at least 600 tonnes rolled down and hit a scaffold, said a spokesman with the Xupu County government.

Of the six workers who were doing construction work at a tunnel portal, two managed to escape and one was killed at the scene. The other three went missing and their bodies were retrieved by rescuers at 1:00 a.m. on Tuesday.

Initial investigation shows that the dislodged rock was caused by a landslide and further investigation is underway.

The expressway, linking Xinhua and Xupu counties, is 92 km long in distance.