The L.A. Police Department had seized some 5,000 pounds of fireworks from 26-year-old Arturo Ceja III before the explosion, but investigators later uncovered a total of about 32,000 pounds — or 16 tons – on the property, the U.S. Attorney’s Office in L.A. said in a news release.

LAPD’s botched detonation injured 17 people — including nine Los Angeles police officers and a federal agent — and left a path of destruction spanning several blocks near the epicenter in the 700 block of East 27th Street, with more than 30 homes destroyed.

LAPD has chalked up the devastating failure to an “apparent miscalculation” of the weight of fireworks placed in a chamber meant to contain the explosion, which was designed to take a maximum capacity of 25 pounds. Investigators later determined more than 42 pounds had been put in.

Ceja pleaded guilty Monday to a single count of transportation of explosives without a license.