[chris]

Emergency dispatchers in McLennan County, Texas, took a rush of 911 calls on the evening of April 17, 2013, as a fire spread through the West Fertilizer Company plant in the town of West, about 18 miles north of Waco. Roughly 20 minutes after the first report of smoke, the plant's stockpile of ammonium nitrate detonated, killing 15 people and injuring more than 200.

The blast came at 7:50 p.m., as volunteer firefighters were pouring water on the flames, according to the U.S. Chemical Safety Board. Investigators estimated its force at the equivalent of 7 to 10 tons of TNT. It flattened homes for blocks, opened a crater about 90 feet wide and registered on seismographs.

Twelve of the 15 who died were emergency responders, most of them volunteer firefighters who had answered the fire call, the board found. The others were residents of the surrounding neighborhood. More than 150 buildings, among them a middle school, a nursing home and an apartment complex, were damaged or destroyed.

Audio of the 911 traffic from that night, later released to the public, records a dispatch center fielding one call after another as the fire grew and then the blast struck. The plant had stored about 540,000 pounds of ammonium nitrate, according to its final filing with the Environmental Protection Agency, a quantity it had not disclosed to the Department of Homeland Security as federal rules required.

In an April 2014 report, the Chemical Safety Board called the disaster preventable and faulted careless storage and a patchwork of weak federal, state and local regulation. "It should never have occurred," the board wrote.

The cause of the fire itself was never resolved. In May 2016 the Bureau of Alcohol, Tobacco, Firearms and Explosives announced it had classified the fire as a criminal act that was intentionally set, and offered a $50,000 reward for information leading to an arrest. No one was ever charged, and outside fire experts questioned the ruling, which the agency reached largely by eliminating accidental causes.

Texas lawmakers passed a measure in 2015 giving state and local officials authority to inspect ammonium nitrate storage. The city of West recovered about $10 million in settlements, and in April 2019 a Fallen Heroes Memorial, a ring of 15 stone markers around a reflecting pool, was dedicated near the ground where the plant had stood.