An 80-metre long section of the bridge collapsed and six vehicles had been retrieved from the debris, China's official news agency Xinhua said, adding that rescue efforts were underway.
The bridge is on the G30 expressway, the longest road in China, which stretches for nearly 4,400 kilometres (2,734 miles) from China's western border with Kazakhstan to the eastern Yellow Sea.
Many of China's roads are packed as the country gears up for its most important holiday, the Lunar New Year, when hundreds of millions of people travel back to their hometowns in what is billed as the world's largest migration.
The season is also a peak period for fireworks producers, as Chinese traditionally buy the explosives to celebrate the festival, which falls this year on February 10.
According to police statistics, around 70,000 people die and 300,000 more are injured in road accidents every year in China, state media have reported.