Los Angeles, California - Police officers were in the process of seizing over 5,000 pounds of illegal fireworks from a home in Los Angeles when they went off, injuring at least 17 people in an accident that is now under investigation.

Police Chief Michel Moore said that the team loaded full pallets of fireworks into specialized containment vehicles, which were supposed to be driven away for a safe destruction at another location.

But it all went wrong. "Something happened in that containment vehicle that should not have happened, and we don’t know why, but we intend to find out why," Moore told CBS Los Angeles, calling the explosion "catastrophic."

The armored truck was supposed to be able to handle the explosives and prevent any damage or harm, should an explosion occur. But the top of the vehicle, which weighed up to a full ton, was sent through the air and smashed through part of a home's roof two blocks away.

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According to the Los Angeles Fire Department, nine LAPD officers had only minor injuries. One Bureau of Alcohol, Tobacco, Firearms and Explosives officer was also hospitalized with minor injuries. Six civilian bystanders were hurt, three seriously so, and all were taken to local hospitals for treatment and evaluation.

Earlier Wednesday, LAPD responded to a tip about illegal fireworks at a home in the 700 block of 27th Street. It seems the homeowner, named by Moore as 27-year-old Arturo Cejas, had purchased the more than 5,000 pounds of fireworks out of state with the intent to sell them to neighbors for the Fourth of July.

Officers also found "improvised explosive devices" and removed them from the home for safe detonation.

Cejas was arrested and given a $500,000 bail, while his younger brother was placed in Child Protective Services.