Nine people were injured by the blast Wednesday evening in the northwest region of Xinjiang, including two who were in critical condition, China Central Television reported.
The accident happened in the Gobi Desert outside the city of Turpan. Footage aired on CCTV showed a large patch of brown sand that had been burned black and several sport utility vehicles reduced to charred shells. One was flipped on its back.
CCTV said 904 boxes of firecrackers had been scheduled to be destroyed. The explosives filled eight trucks, the Xinhua News Agency reported.
The blaze was extinguished after about an hour, though firefighters had to work from a distance because some fireworks had not exploded, CCTV reported.
Victims included police officers and local journalists who had gone to cover the event, Xinhua reported.
The cause of the accident was under investigation. Numerous government and hospital officials contacted by The Associated Press said they had no additional details.