Horrible to see that, it might have been hit by a car or something heavy or maybe a fall (roof), the bleeding at the mouth might mean internal injuries where it eventually died, I saw this a few years back when doing an early morning milk round.
The cat got hit by a car and managed to crawl onto the footpath where it eventually died through internal injuries, blood coming from its mouth, we managed to find out who owned the cat (collar with name and address on it) and we informed them who buried it in their garden.