Raise revenue by ticketing violators
However, I noticed the reported location of this incident appears to be in unincorporated Snohomish County -- where personal fireworks are only legal to discharge on July 4 (Snohomish County Code 30.53A.722).
They're also only legal on July 4 in the nearby city of Lake Stevens (Lake Stevens Municipal Code 9.64.020). The penalty for violating the Lake Stevens ordinance is a potential $1,000 fine, and the fine in unincorporated county used to be $500-$1000 but I can't find it now. In Everett and several other Snohomish County cities, personal fireworks are not legal to set off any day of the year -- though even this easy-to-understand rule is flouted by many.
With all the budget problems our county and cities have been experiencing in recent years, it seems that a significant amount of revenue could be obtained by seriously cracking down on the inconsiderate fireworks outlaws who refuse to confine their noisy and hazardous activities to the allowed days and times. Let the word go out from the various county law-enforcement agencies: No more friendly warnings or reduced fines about fireworks -- all violators will receive the maximum fine on their first "strike".