Bomb squad officers who detonated a massive cache of illegal fireworks in Southern California last month, causing a "catastrophic" blast that injured 17 people — including nine officers and a federal agent — appear to have misjudged how much explosive material they were blowing up, authorities said Monday.
The Los Angeles police officers believed they were detonating about 16 pounds of material during the controlled blast in a neighborhood June 30, Police Chief Michel Moore told reporters.
But preliminary findings from the Bureau of Alcohol, Tobacco, Firearms and Explosives found that they are likely to have detonated more than 42 pounds of explosives, he said.
The device used for the controlled explosion, called a "total containment vessel," was designed to withstand a maximum capacity of 25 pounds of C4 explosives, Moore said.
"We have miscalculations that are significant," Moore said.
Following established practices, the officers did not weigh the explosives before they detonated them because of how unstable they were, he said. Instead, they estimated the weight and used a remote robot and X-rays to examine the devices.
Among them were 280 M-80s and 44 devices that were the size of soda cans, he said, adding that the officers also appear to have miscalculated the weight of the explosives they used to cause the controlled blast.
Moore said the explosion that followed was "catastrophic," causing 17 non-life-threatening injuries and damaging or destroying 13 businesses, 22 homes and 37 cars.
"We're committed to identifying how this occurred and ensuring it never happens again," he said.
Reviews of the bomb squad's practices are underway, he said, and the officers and the supervisor involved were removed from the field. Moore said the apparent miscalculation was made in "good faith," although he added that if "mistakes were made, I'll hold the individuals accountable."
The controlled detonation occurred after authorities found 32,000 pounds of illegal fireworks in the backyard of a South Los Angeles home. The M-80s and other devices were placed in the containment vessel after investigators determined that they were too dangerous to remove.
The suspect accused of buying the fireworks in Nevada and storing them at his home was charged this month in federal court with transporting explosives without a license.