NINGXIAN - A bus crash that killed 18 people and injured 32 others on Friday in Northwest China's Gansu province was caused by driver error, police said Monday.

An investigation showed that driver Feng Tao was not aware of a sign indicating a sharp turn on a mountain road, said a police officer with the public security bureau of Ningxian county.

The accident happened around 10 pm Friday, when 54 people were on the 47-seat bus. The bus went off the road, fell into a ravine and caught fire.

The passengers were migrant workers and their relatives heading to Ningxian and other nearby counties in the city of Bazhou in Hebei province.

The injured, including Feng, are still receiving treatment at a local hospital.

More road accidents have occurred in the last week, as millions of people are traveling to visit their families for the approaching Spring festival holiday.

Five major traffic accidents occurred from Jan 31 to Feb 1, killing 60 people.