A crane mounted to the side of a skyscraper under construction toppled with a roar Saturday, smashing into a block of apartment buildings. Mayor Michael Bloomberg said at least four people have died and at least 10 people were injured in one of the city's worst construction accidents in recent memory. An intensive, but delicate rescue operation was under way to find anyone still trapped in the several-stories-high piles of rubble. John PlaGreco, who owns Fu Bar in the crushed building, said he feared one of his employees was dead inside. "Our bar is done," he said. "The crane crashed the whole building. If I wasn't watching a Yankees game, I would've come to work early and gotten killed."