Why is Parris afraid for his life? what does he think the action means?(how does salem feel?)

Someone inserted a dagger into the wood of Parris' front door; it was a warning. He believes that his life is in danger.

Parris: Tonight, when I open my door to leave my house—a dagger clattered to the ground. Silence. danforth absorbs this. Now parris cries out: You cannot hang this sort. There is danger for me. I dare not step outside at night!