A bus travelling on an expressway has scraped a car, crossed the centre divider and smashed into another oncoming bus, Chinese state media said. That bus then veered off the road, killing 13 people on board.
The accident occurred around noon on Sunday in eastern Shandong province.
CCTV says the second bus rolled over as it fell down a slope from the expressway.
Xinhua News Agency says 13 people on that bus died and nine others are seriously injured.
A man on duty at the Shandong provincial traffic management bureau says the accident is still being investigated.
The total number of passengers onboard the bus, with a capacity of 53 passengers, remains unclear.
Millions of travellers were on the road on Sunday as they returned home at the close of the eight-day national holiday. Transport authorities and traffic police were on high alert.