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.
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.