The novel I am writing hinges on an orphan boy, who is not evil, but merely frustrated and angry with the world and how it is treating him. I need him to do something or cause something to happen that inadvertently kills many of the people in his town. This causes another of the main characters, also a child, to resent him and to be unable to forgive him.
I want this story to be in a fairly modern time period, preferably in the United States. It would be better if thing this boy did, let's call him Bob, would be something that didn't necessarily result in a prison for life sentence or something similar, or if it did, couldn't be directly traced to him. Maybe Bob's action could be considered an accident or a result of stupidity or someone else's carelessness in allowing it to happen. The other character, I'll call her Maya, would recognize that it was Bob's fault in some way. Again, Bob's actions do show his anger, but he did not genuinely intend to kill many people.
What I am asking for is a specific example of a scenario that could cause such a thing. I have no problem or question about how the characters interact, just about explaining this event in the past.