The fertilizer plant explosion that killed 15 people and injured more than 200 others at a small town in the US state of Texas a year ago could have been prevented, a US federal agency said Tuesday in its latest report.

The US Chemical Safety Board, charged with investigating industrial chemical accidents, released its preliminary findings of the April 17, 2013 explosion at a press conference in Dallas, Texas Tuesday.

Board Chairman Rafael Moure-Eraso said in a statement that the explosion, which leveled hundreds of buildings and decimated parts of the town, could have been averted had the fertilizer company taken necessary safety measures.

"The fire and explosion at West Fertilizer was preventable,"

Moure-Eraso said. "It should never have occurred. It resulted from the failure of a company to take the necessary steps to avert a preventable fire and explosion and from the inability of federal, state and local regulatory agencies to identify a serious hazard and correct it."

The chairman said his agency found significant holes in regulations regarding the storing of hazardous chemicals, which "without a doubt" caused the West Fertilizer explosion last year.

The board also found that the plant was storing up to twice as much ammonium nitrate as originally reported -- 40 to 60 tons rather than the 28 to 34 tons originally cited. It's a chemical component commonly used in fertilizer and as an industrial explosive.

Volunteer firefighters from West were not aware that the ammonium nitrate stored at the fertilizer offered an additional explosion hazard, which placed them in harm's way during the blast, the investigators said. Among the 15 people who died in the incident, 14 were firefighters.

It's as yet unknown what exactly caused the initial fire that led to the deadly blast. No one has been charged in connection with the blast.