Some West residents expressed disbelief and frustration Thursday after federal investigators announced that the fire that caused the deadly and destructive fertilizer plant explosion in April 2013 was intentionally set.

(Photo by Clint Webb)

"I know I'll never believe it. I didn't think it was true when I heard it the first time,” longtime resident Coranell Womack said.

The Bureau of Alcohol, Tobacco, Firearms and Explosives announced the findings during a news conference Wednesday in West.

“This fire was a criminal act,” ATF Special Agent in Charge Robert Elder said.

The only hypothesis that couldn’t be eliminated through investigation and testing was that the fire in the seed room of the fertilizer plant's building was incendiary, he said.

Investigators reached that conclusion after conducting more than 400 interviews and sifting through mounds of evidence and photos.

"All viable accidental and natural fire scenarios were hypothesized, tested, and eliminated," Elder said.

What investigators don't know is the intent of the person responsible for the fire, officials said.

Food Mart clerk Tony Hill said he just shook his head when he heard about the announcement.

“I don't buy what they said.”

Neither does Charles Jubacak, who was meeting with a number of senior citizens Thursday at the West Community Center.

“I don't quite buy that myself,” he said.

Elder said the fire investigation, on which about $2 million was spent, was one of the largest in the history of the ATF.

“We have never stopped investigating this fire,” he told reporters.

No arrests have been made, and the ATF is offering a reward of as much as $50,000 for information leading to the person responsible for the fire.

Waco Crime Stoppers added another $2,000 to the reward.

Bryan Anderson, who owns and operates The Pizza House, questions whether the three-year fire investigation produced anything concrete.

“It almost feels like they're grasping at straws if you spent $2 million and you interviewed 400 people and you still don't have anything," he said Thursday.

“If they had anything they wouldn't be here begging for help for somebody to turn somebody in that may not exist," he said.

Anderson and his 9-year-old son were in Anderson’s pickup and driving toward the fertilizer plant when the explosion occurred.

The force of the blast tossed the truck off the road and onto the lawn of the West Rest Haven nursing home, which the explosion destroyed.

“When it happened I couldn't see he couldn't see and we were just grabbing for each other and he was screaming ‘dad are we dead, are we dead’ and there was a short moment, but I told him ‘I don't know son, but if we are we're dead together.’"

"It sucked everything in on us and then blew us across the road and it was horrendous there's memories that I would like to erase that we can't."

The powerful explosion on April 17, 2013, left 15 dead including 12 first responders, injured more than 200 and damaged or destroyed hundreds of homes and buildings including a nursing home, a two-story apartment building and three of West’s schools.

The blast affected a 37-block area and left a crater 90 feet wide and 12 feet deep.

A preliminary investigation completed about a month after the explosion identified three possible causes of the fire, two accidental and the third intentional.

In May 2013, investigators said they had determined that the fire was caused either by a battery-powered golf cart that was kept in the fertilizer and seed building in which the fire started, the building’s 120-volt electrical system or by an intentional criminal act.

The tragedy unfolded in just 19 minutes.

The fire started at 7:29 p.m. on April 17, 2013.

West firefighters were dispatched to the plant at 7:32 p.m., arrived at 7:38 p.m. and requested assistance from other departments at 7:41 p.m.

The plant exploded at 7:51 p.m.

As much as 64 tons of ammonium nitrate was stored in the building, 28 to 34 tons of which exploded.

An additional 20 to 30 tons in the building and another 100 tons in a nearby railcar did not explode.

By comparison, the amount of ammonium nitrate that exploded on April 17 in West was about 12 times the amount used in the truck bomb that blew the side off of the Albert P. Murrah federal building on April 19, 1995 in Oklahoma City.

In January, the U.S. Chemical Safety Board presented its report on its investigation of the deadly explosion, which included 18 safety recommendations aimed at preventing future such disasters.

The 265-page report said the town’s fertilizer plant lacked safety features that could have prevented the blast and says first responders weren’t adequately trained on how to respond to the fire that triggered the detonation.

The explosion was the result of “poor hazard awareness, regulatory oversight, inadequate emergency planning and the proximity of the facility to schools and neighboring communities," CSB Chairperson Vanessa Allen Sutherland said.