The explosion took place at a rice noodle restaurant in the provincial capital Kunming as a delivery van packed with liquefied gas containers was parking at the door.
Police began transferring the bottles to another pickup truck as soon as they reached the scene.
"The fire was put out soon after the fire trucks arrived," a witness surnamed Sun said.
"Several people rushed out from the restaurant with their hands clenched on their chest or heads, blood flowing through their fingers."
According to the local police, one person was seriously injured and the rest suffered minor wounds.