File:Airplane Day-Feds- Fire Downed WTC Building 7.png

http://www.cbsnews.com/stories/2008/08/21/national/main4371289.shtml

(AP) Federal investigators said Thursday they have solved a mystery of the Sept. 11, 2001 attacks: the collapse of World Trade Center building 7, a source of long-running conspiracy theories.

The 47-story trapezoid-shaped building sat north of the World Trade Center towers, across Vesey Street in lower Manhattan. On Sept. 11, it was set on fire by falling debris from the burning towers, but skeptics have long argued that fire and debris alone should not have brought down such a big steel-and-concrete structure.

Scientists with the National Institute of Standards and Technology say their three-year investigation of the collapse determined the demise of WTC 7 was actually the first time in the world a fire caused the total failure of a skyscraper.

"The reason for the collapse of World Trade Center 7 is no longer a mystery," said Dr. Shyam Sunder, the lead investigator on the NIST team.

Investigators also concluded that the collapse of the nearby towers broke the city water main, leaving the sprinkler system in the bottom half of the building without water.

The building has been the subject of a wide range of conspiracy theories for the last seven years, partly because the collapse occurred about seven hours after the twin towers came down. That fueled suspicion that someone intentionally blew up the building in a controlled demolition.

Critics like Mike Berger of the group 9/11 Truth said he wasn't buying the government's explanation.

"Their explanation simply isn't sufficient. We're being lied to," he said, arguing that there is other evidence suggesting explosives were used on the building.