ZHENGZHOU, Jan. 9 -- Six people were killed and two others injured in four separate accidents that occurred on an expressway in central China's Henan Province Thursday morning, local traffic police said.

The accidents happened during the period from 9 a.m. to 11 a.m. on different sections of the Daqing-Guangzhou Expressway in the city of Xinyang, the police said.

The injured are now in stable condition.

Poor visibility caused by heavy fog resulted in the four accidents, according to the police. Further investigation is under way.