Four people were found dead in a cave of an abandoned colliery in Heibei Province Friday, the local government said Saturday.

A preliminary investigation indicated no signs of mining, explosion or electricity using in the cave in Laiyuan County, according to the county government.

The four were believed to have died of suffocation due to lack of oxygen, according to the work safety supervision administration of the county.

Investigators were trying to ascertain the identities of the victims.

(Xinhua News Agency August 15, 2009)