Seventeen people, including 10 law enforcement officers, were injured and several cars and houses were damaged Wednesday night when police attempted to safely detonate illegal explosives seized in South Los Angeles.

None of the injuries were life-threatening, and homes did not immediately appear to have serious structural damage, police said.

A 27-year-old man was also arrested, accused of importing the fireworks from out of state with plans to resell them for the July 4th weekend.

The explosion in the Historic South-Central neighborhood came around 7:30 p.m., as bomb squad personnel aimed to detonate a confiscated device within an iron-chambered containment vehicle.

Police working off an anonymous tip had discovered an estimated 5,000-pound stash of commercial-grade fireworks around 8:40 a.m. that morning. They later found a set of smaller, improvised explosives with simple fuses, which they evaluated to be less stable.

Authorities spent much of the day transporting the fireworks away from the site. Following protocol, police said, the bomb squad opted to detonate less than 10 pounds of the improvised explosive within the armored vehicle, which is rated to safely contain more material than that.

The force of the explosion instead destroyed the container and caused damage to several cars parked on the street.

“You saw the resulting damage, and the total catastrophic failure of that containment vehicle,” LAPD Chief Michel Moore said Wednesday night.

Nine Los Angeles Police Department officers and one Bureau of Alcohol, Tobacco, Firearms and Explosives special agent suffered minor injuries, according to the Los Angeles Fire Department. Three residents were hospitalized with serious injuries and three others with minor injuries. One person was assessed for injuries but not transported.

Several homes were damaged by the explosion and Los Angeles Department of Building and Safety personnel are evaluating them to determine if anyone will need emergency shelter.

The blast took neighbors by surprise. Some took cellphone video of damage, shattered windows and glass shards scattered in their homes, grateful they survived the blast.

“It felt like pretty much a giant bomb pretty much going off,” Thomas Mendez said. “Felt like a wave going off, explosion. The pressure. If you had been closer you would have been injured.”

Mendez said it was traumatizing for the kids.

“My son, autistic,” he said. “Dropped to floor as he was playing around.”

It was not immediately known why the containment of the detonation of the fireworks failed.

“I’ve directed the LAPD to conduct a full investigation into this incident, so we can better understand why this happened,” Los Angeles Mayor Eric Garcetti said in a tweet Wednesday evening.

Police arrested Arturo Cejas III. Cejas, who is in his 20s, was arrested on suspicion of reckless or malicious possession of a destructive device and is being held on $500,000 bail, LAPD Officer Tony Im said.

He may face more charges for child endangerment because his 10-year-old brother lives with him at the home, police said.

Illegal fireworks have been a growing problem in Los Angeles. The year 2020 was a particularly bad one, as citizen complaints skyrocketed across the city and county..

On July 4, 2020, there were nearly 2,800 reports — online and phone calls — to the LAPD reporting illegal fireworks. Fireworks led to “numerous fires” according to LA Fire officials including a blaze at a Northridge apartment complex that displaced 50 people. 

Officials reported issues ahead of last year’s holiday, which mirrored complaints around the country.

That, coupled with an explosion in March due to illegal fireworks rocked an Ontario neighborhood, led public officials to vow a crackdown against the increasingly powerful explosives that individually or collectively present a clear and present danger to neighborhoods where they are illegally kept.

NBC4’s Beverly White, NBC Investigation’s Andrew Blankstein and the NBC4 I-Team’s Eric Leonard contributed to this report.