Witnesses who could shed light on the cause of deadly Tennessee blast were killed

Obed Lamy/AP via CNN Newsource

(CNN) — 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.

The cause of Friday’s explosion is still under investigation, but authorities caution answers may not come for weeks or months due to unique challenges that will require a delicate, methodical approach and “minute-to-minute” safety evaluations.

Undetonated explosives pose a serious threat to first responders and investigators. The manufacturing facility, Accurate Energetic Systems, lies roughly 60 miles west of Nashville and crafts highly explosive products for the military and indust