The Houston Field Division of ATF and the Texas State Fire Marshal’s Office hosted a news conference announcing the cause of the West Fertilizer Plant fire and explosion that occurred on April 17, 2013.

ATF concluded the fire took the lives of 15 people, 12 of whom were fire fighters or first responders.  ATF said it was intentionally set and has been deemed a criminal act.

Officials believe the fire was intentionally set when then led to the explosion.  But specifically who and why — officials did not know that yet.  As for murder charges, officials again said it was too early to say. 

In addition to the fatalities, 260 people were injured. No arrests have been made. The ATF was offering a reward of up to $50,000 for information leading to the arrest of the responsible party.

The blast caused widespread damage to more than 150 nearby buildings. The explosion is one of the most destructive incidents ever investigated by the U.S. Chemical Safety and Hazard Investigation Board as measured by the loss of life among emergency responders and civilians.

The facility had a stockpile of between 40 and 60 tons of fertilizer grade ammonium nitrate (FGAN).

More than half of the structures damaged during the explosion were demolished to make way for reconstruction. The demolished buildings include an intermediate school, a high school, a two-story apartment complex with 22 units and a 145-bed nursing home.

The owners of the West Fertilizer Co. had $1 million in liability coverage, but the damage from the explosion exceeded $200 million. Following the explosion, WFC filed for bankruptcy.

In October, a settlement was reached with families of victims of the explosion and the owners of the facility. The terms of the settlement were not disclosed.

(MyCenTx.com contributed to this report)