Local authorities say 26 people have been killed and 28 injured after a tour bus caught fire on a highway in central China's Hunan province.

The provincial spokesman's office said Saturday that five of those injured were in critical condition.

The incident occurred at around 7:15 p.m. (1115 GMT) Friday along a stretch of Hanshou County in the city of Changde. Aboard were 56 people, including 53 passengers, a tour guide and two drivers, both of whom have been detained as authorities investigate the cause of the accident. Changde authorities put the number of injured at 30.

Photos from the scene show the 59-seater bus's interior completely charred, possibly indicating the fire started with materials on board. Industrial and transport safety remain major problems in China.