China Explosion-proof test equipment mounted in an oil refinery in Yan'an, Shaanxi, killing 5 people, injuring 8 and missing.

The explosion occurred at 7pm on October 27, when the car from the oil field returned to the Yilang Qilicun factory in Yanzhong County, Yan'an City, Shaanxi Province, an area rich in oil and natural gas in China.

Five injured were treated at the hospital and in stable condition, while three others were missing, local officials said today.

The blasted car belonged to a thermo-technology company in Hunan province and regularly carried equipment to carry out factory tests.

Rescuers are looking for the missing. Officials are investigating the cause of the explosion.