The state fire marshal's office had previously ruled out four potential causes: weather, natural causes, anhydrous ammonium and ammonium nitrate in a rail car.
CNN: Cause of catastrophic Texas explosions remains mystery
2.
The fire began in the fertilizer and seed building, but authorities still were trying to figure out the exact spot, the fire marshal's office said Monday.
CNN: Criminal probe started into Texas fertilizer plant blast
3.
On Monday, the state fire marshal's office said it ruled out four potential causes: weather, natural causes, anhydrous ammonium, and ammonium nitrate in a rail car.
CNN: Criminal probe started into Texas fertilizer plant blast