GUIYANG -- Twenty-four people were seriously injured in a natural gas pipeline explosion in Southwest China's Guizhou province Sunday night, local authorities said Monday.

Gas leaked from a section of the gas pipeline operated by PetroChina in Shazi town of Qinglong county and then caused an explosion and fire at about 11:20 p.m. Sunday, the county government said.

The pipeline was automatically shut down after the explosion and the fire was put out at 2:30 am Monday.

No deaths have been found. Of the 24 hospitalized, eight were in critical condition and 16 in serious condition, but the injuries were no life threatening.

Local rescuers were still searching to see if there are more casualties.

An investigation into the gas leak is under way.