The official Xinhua News Agency said the explosion happened near an expressway ramp in Fuquan city in Guizhou province and knocked down several homes. It did not immediately give any other details about the midday explosion.
A man who answered the phone in the press office at the city's Communist Party branch said three vehicles carrying explosives caught fire at a garage and exploded. The man, who like many Chinese officials would not give his name, put the death toll at at least three, and said the blast destroyed the garage and a crop warehouse.
"I can't really tell how many went missing because it is a total mess over there at the explosion scene. Over 100 people were hurt and sent to several hospitals," he said after returning from the scene. The official did not say why the vehicles were carrying explosives or what they were.
He added that heavy equipment was being used to search through the wreckage.
Accidents and explosions are common in China due to weak safety standards and lax building practices.