People are being warned to only buy fireworks from licensed retailers after a white van crammed with them was discovered in Bristol.
Trading Standards said they had not been stored properly and could be very dangerous.
A spokesman added that people purchasing fireworks from places such as car boot sales and pub car parks were also "asking for trouble".
Buyers can ask to see a shop's licence certificate to legally sell fireworks.
Phil Parkyn, the city council's principal trading standards officer, said the van was found in Muller Road on Wednesday.
"Fireworks are explosives and have to be stored correctly and treated with respect," he added.
The department is also reminding shopkeepers that it is illegal to sell fireworks to people aged under 18.