A mattress fire mushroomed into a two-alarm blaze at a Brooklyn YMCA, forcing one man to jump to his death and fatally burning another over his entire body, authorities said. Eleven others were injured.

One of the men leaped out of a third-floor window at the brick residence as firefighters attempted to battle the blaze, authorities said Sunday. Another resident died Sunday at New York University-Cornell Medical Center's burn unit after sustaining burns over 100 percent of his body, a spokesman there said.Seven other residents, two firefighters and two police officers were also injured in the Saturday blaze at the YMCA residential hotel.