The official Xinhua News Agency said 39 people were on the long distance sleeper bus when it crashed and only three survived. The survivors were hospitalized, it said, but didn't say what condition they were in.
The tanker had just returned to the highway after an early morning rest stop when it was apparently rear-ended by the bus at around 2:40 a.m. close to the city of Yan'an in Shaanxi province, the official China News website said.
The bus had left Hohhot in Inner Mongolia at 5 p.m. Saturday and was headed south to Xi'an city, it said.
Xinhua news photos showed the charred metal skeleton of the bus rammed up against the back of the tanker.
An official with the local Communist Party propaganda bureau in Yan'an confirmed that the crash occurred but was unable to give details and was unsure of the death toll.
Road safety is a serious problem in China. According to Xinhua, poorly maintained roads and bad driving habits result in about 70,000 deaths and 300,000 injuries a year.