ZHENGZHOU, April 1 -- Seven people died and another was critically injured in a series of car crashes in central China's Henan Province, police with Xinyang City said Saturday.

The accident occurred early Saturday at an expressway section in Xixian County of Xinyang. More than 40 vehicles were involved in the crashes, which happened within a two-km-long area. Eight people were trapped in six separate vehicles, the police said.

Three fire engines and 17 fire fighters were sent to rescue the people. Seven died at the site and one person was gravely injured and sent to the hospital.

Fog and low visibility are suspected to be the cause of the accident. Further investigation is under way.