High-visibility police patrols which began over Halloween are continuing up to and during Bonfire Night in Surrey.
Surrey Police said troublemakers were in the minority over Halloween, but patrols would still be stepped up.
Officers will be targeting parks and public areas and will confiscate fireworks if anyone under 18 is found carrying them.
Test purchases have been carried out across Surrey to check retailers are complying with the law.
Surrey trading standards officers said so far no underage sales had been made.
Supt Sharon Bush said she wanted to remind people that setting off fireworks in a public place or throwing them at people was illegal and dangerous, and could lead to someone being seriously injured along with a £5,000 fine or a prison sentence.