Alternatively, they’ve thought beforehand and placed the sign knowing that some may also want to get rid of their grenades. But as they require extra care, it’s probably a bad idea to store them in a container in the foyer of the police station.

I assume the container is regularly checked. probably daily.

Also. There’s always a story behind every warning sign like that. One might have just showed up. one might have gone off. but something happened to make someone go, “maybe we should get a sign.”