Beijing (CNN) Slippery conditions and fog are thought to have contributed to a huge highway pileup that killed 17 people in northeastern China.

The crash involved 56 vehicles on the Beijing-Kunming highway in China's Shanxi province around 9 a.m. Monday, according to state news agency Xinhua.

"The fog was heavy, so I drove slowly when I exit the tunnel," one driver involved in the incident told state-run CCTV. "I saw two vehicles horizontally blocking the road, so I stepped on the brake."

Aerial view of damaged vehicles after the pile-up on the Beijing--Kunming Expressway in north China's Shanxi province.

It had been snowing and raining before the accident, which also injured 37 people, Xinhua said.

Firefighters told CCTV that when they arrived they fought a blaze at the front of the pileup.

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