LAPD bomb squad 'miscalculated' weight of homemade fireworks when 'controlled' detonation went horribly wrong destroying armored truck and leaving 17 people injured Los Angeles police said Monday that an 'apparent miscalculation' by its bomb squad is what caused a June 30 fireworks explosion that left 17 injured LAPD Chief Michel Moore said officers overloaded a 'total containment vehicle' designed to safely detonate illegal fireworks, causing the device to burst open The vehicle is designed to contain 25 pounds of explosives, and officers estimated they were putting in 16.5 pounds in to it But investigators who weighed the debris estimate about 42 pounds of fireworks had been loaded into the device