Halakhah к Шмот 22:5

The commandment on the court to judge damages from fire: To judge and obligate one, who has damaged his fellow with fire, to pay - for example, [if] he lit his stockpile or burned anything of his - as it is stated (Exodus 22:5), "If a fire goes out, etc." The understanding of "goes out" implies even if it went out on its own (Bava Batra 22b), and it comes to warn even if one lit [a fire] on his own [property] and it went out on its own and it damaged, that he is liable - since he did not watch his coals. As a man is obligated to watch his fire that it not [spread] and damage, since it is the way of fire to spread on its own, even though it is not a living being.