WACO - The explosion that killed 15 people and injured hundreds three years ago in West should have been prevented, and something like that should never happen again, the U.S. Chemical Safety Board said at a press conference Thursday morning.

Vanessa Sutherland, the chairperson of the CSB, unveiled the agency's 265-page final report on the accident and encouraged everyone to respond to the recommendations.

Gaps in regulatory oversight must be closed, communities must be better prepared and companies must take the right steps to improve safety or "it is possible for another incident like this to happen," she said.

Johnnie Banks, the supervisory investigator, said it was a "long and incredibly, technically challenging" investigation, which is why is took nearly three years to complete.

He said firefighters racing into the West Fertilizer Company on April 17, 2013 had no time to respond.

"The firefighters did what firefighters do – go where no one else wants to go," he said.

The CSB's report describes a host of failures by the West Fertilizer Company, the government, fire officials, insurance companies and others that allowed tens of thousands of pounds of ammonium nitrate to detonate. The blast destroyed homes, schools, apartments and a nursing home. Had it happened earlier in the day, with school in session, hundreds more people would likely have been killed and injured, the CSB concluded.

Fire investigators narrowed the cause of the blast to three possibilities: electrical wiring, a short-circuited golf cart or arson.

Lawsuits involving hundreds of plaintiffs, including the city of West, remain pending against the plant owners and fertilizer suppliers. The blast caused an estimated $230 million in losses. West Fertilizer is no longer in business.

The CSB, which has no enforcement authority, found that almost all Texas fertilizer plants like the one that exploded are within a quarter-mile of a residence, and little has been done to protect those people.

The agency recently decided to launch a study on the threat of hazardous materials located close to the public. Sutherland said that decision was driven by the fact that 13 past investigations have involved facilities near homes and the threat of a large-scale disaster is still present.