Boy k!lled after setting off fireworks in backyard

A 17-year-old boy was k!lled after a high-powered, illegal firework exploded in a backyard. The explosion rocked the neighborhood with a blast so powerful residents thought it was a bomb.  The explosives detonated around 9:30 p.m. at a home on the 400 block of West 84th Street in the Vermont Knolls neighborhood of South LA late Wednesday, Dec. 3, according to the LAPD.  First responders found the boy in critical condition, and he was pronounced de@d shortly after arriving at a local hospital. Investigators at the scene discovered a box labeled Cash Game 357, a massive 357-shot aerial known for unleashing a rapid-fire barrage of continuous explosions.  The heavy-duty cake firework is illegal in California, where even smaller safe and sane fireworks are heavily regulated.  However, its not immediately clear if that specific firework went off, and investigators have not confirmed what kind of explosive it was that k!lled the boy. The LAPD Bomb Squad, Hazardous Materials Unit, and detectives from the Major Crimes Division all responded to the scene to investigate the area after the blast.  The department assured the public that there were no ongoing safety concerns, seized a large quantity of illegal pyrotechnic devices, and took any explosive material to a safe storage location.