Elders? They've got a ton of ghouls and are probably primogen so you're looking at a real quick Blood Hunt. Especially since their resting place is fireproofed or likely not where you think it is. It'll be dark by the time they emerge from a burning wreckage or definitely by the time they emerge from their actual Haven. Then they interrogate witnesses/ the local Nosferatu and appear a few nights later outside your Haven and ask who torched their house.

Nosferatu? Likely own the homeless population and have bolt holes in a dozen rooms to get out. Then every underworld person in the city has a fat bounty on your head.

But the big reason arson in a city is bad is that when you have a dense city of buildings so crammed together, arson can quickly become a mass murder. The Prince probably isn't going to care if you killed 400 people in the process, just that you killed a vampire without his blessing. Your Humanity however...