The Texas fertilizer plant explosion that killed 15 people a year ago could have been prevented — and agencies at all levels haven't done enough to change the circumstances that led to the catastrophe, federal officials said Tuesday.

The U.S. Chemical Safety Board presented its preliminary findings about the blast in West, Texas, in front of a packed room of residents and town officials still rebuilding after the April 17, 2013, explosion leveled part of the tiny town and injured 200 people.

Even though several investigations have not determined the exact cause of the fire, the board says it's clear the owners of West Fertilizer Co. failed to safely store hazardous chemicals or prepare for a potential disaster. The board also said several levels of federal, state and local government missed opportunities to prevent the tragedy.

Investigators said the firefighters who rushed to an initial fire at the plant didn't know enough about the dangers they faced inside: 40 to 60 tons of ammonium nitrate, a chemical used in fertilizer that detonated due to the blaze.

But experts on a panel convened by the safety board said Tuesday night that even if the firefighters had known more, there still isn't clear guidance on what to do in that kind of situation.

Glenn B. Corbett, a professor at the City University of New York who is a fire safety expert, faulted guidelines that suggest firefighters should try to douse such a fire until it becomes "massive," a term he said was too vague to determine in an emergency.

"It is best to simply move everyone back and let the fire burn itself out," Corbett said.

There was also a gap between U.S. and Texas agencies on whether the fertilizer plant needed to comply with federal guidelines on disaster preparedness due to its stores of ammonium nitrate, safety board investigator Rachael Gunaratnam said. That disconnect "left emergency responders and residents unprepared for April 17," she said.

Among those in the audience was West Mayor Tommy Muska, a volunteer firefighter who responded the night of the blast. Muska thanked the board for holding its meeting in the city.

"It is my personal hope and prayer that the lessons learned from your report ... will be enacted, and measures put in place so that the loss of the first responders' lives will not be in vain," Muska said.

Despite investigations that have yielded information about safety deficiencies at the plant and voluntary safety steps taken by the nation's fertilizer industry, not a single state or federal law requiring change has been passed since April 17, 2013.

An ongoing investigation by federal and state officials has narrowed the possible causes of the fire to three things: a golf cart battery, an electrical system or a criminal act. No one has been charged.

Board Chairman Rafael Moure-Eraso said federal, state and local agencies could all do more. He said he believes the U.S. Environmental Protection Agency has enough authority already to require companies to follow stricter guidelines.

"The fire and explosion at West Fertilizer was preventable. 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," Moure-Eraso said.

In Texas, companies can still store hazardous chemicals in flammable wooden containers in buildings without sprinklers, and volunteer firefighters still aren't required to train how to fight such blazes.

Moure-Eraso suggested Texas could change the law to allow small counties to enact their own, and said officials in McLennan County, where West is located, could have done more to prepare an emergency response plan for the plant.

But he laid the ultimate responsibility for preventing the disaster on West Fertilizer Co.

"What the regulators do is basically monitor what is happening, but the primary responsibility has to be for whoever is putting this chemical in commerce," Moure-Eraso said. "The regulators themselves are not the ones that caused this thing."

A spokesman for the owners of the plant did not respond to a message. The owners have denied allegations that the plant was negligent in how it handled and stored ammonium nitrate.

Al Jazeera and The Associated Press