"Between the years 1979 and 2002 there were over 180 firefighter fatalities due to structural collapse, not including those firefighters lost in 2001 in the collapse of the World Trade Center Towers. Structural collapse is an insidious problem within the fire fighting community. It often occurs without warning and can easily cause multiple fatalities. As part of a larger research program to help reduce firefighter injuries and fatalities the U.S. Fire Administration (USFA) funded the National Institute of Standards and Technology (NIST) to examine records and determine if there were any trends and/or patterns that could be detected in firefighter fatalities due to structural collapse. If so, these trends could be brought immediately to the attention of training officers and incident commanders and investigated further to determine probable causes."
United States Fire Administration: http://www.usfa.dhs.gov/