Tennessee explosives plant: Challenges investigators are facing in determining what caused the deadly blast

Utter devastation lies before investigators days after a building at a Tennessee explosives plant was razed by a blast so powerful that it left behind no living witnesses, created a vast and volatile investigative scene and cast potential evidence for miles around.

​ Utter devastation lies before investigators days after a building at a Tennessee explosives plant was razed by a blast so powerful that it left behind no living witnesses, created a vast and volatile investigative scene and cast potential evidence for miles around. Read More Breaking News, Latest News and Videos | CNN