Purim is a dangerous time. Not just because of all the drunks on the road (whether by car or by foot), but also because of firecrackers and other dangerous materials.

In Israel firecrackers and other such paraphernalia is popular among the kids on Purim. In recent years there have been campaigns against it, considering how dangerous they are, and the numbers seem to have gone down drastically, but they still get sold all over and there are still kids buying these things, and you can often hear the explosions around town in the days leading up to Purim, until shortly after. And sadly we hear in the news every now and then about bad accidents as a result with kids losing fingers or eyes to these things.

Rav Dovid Yosef announced a psak that it is a mitzva for people to report to the police when they know of someone selling firecrackers.

Rav Yosef says these are a terrible danger - it can cause tragedies to pregnant women or to other people getting frightened from the firecrackers exploding nearby, in addition to hearing every year about people who lost fingers or became blind from them, without even getting itno a discussion of damage caused to private property.

Rav Yosef said because of the danger one is not allowed to sell them, but we can't go burn down such a store that does. We must first warn him to stop and if he continues to sell we must report him to the police.
source: Kikar