Reports Sunday say the operator of the stand in the southern region of Guangxi has been formally arrested on the criminal charge of causing an accident through the use of dangerous articles.
Those killed in Tuesday's accident included three children and two adults.
Prosecutors say the stand's operator, identified only by his surname, Zhang, was negligent in storing the fireworks in a pile outside his grocery, leaving them prone to being easily ignited by a spark or stray cigarette.
China has cracked down heavily on the production and sale of fireworks, formerly a major part of celebrations for the Lunar New Year, which this year fell last week.
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