NANNING -- Four people were killed and 31 others injured when a bus hit a truck in south China's Guangxi Zhuang autonomous region Saturday night, local authorities said Sunday.

The sleeper coach from Dongguan in Guangdong province to Guigang in the neighboring Guangxi was carrying 44 passengers. The accident happened when a truck loaded with sand collided with the bus at 11 p.m. Saturday.

Two people in the truck, including the driver, and two others on the bus were killed.

Another 31 were injured, two of whom were described as "serious" by rescuers.

Traffic resumed Sunday morning six hours later the accident, and its cause is under investigation.

This is the second fatal road accident involving a truck and bus in Guangxi this month. On Aug 14, a truck driver died when his vehicle crashed into a bus, with 23 others taken to hospital.