SOUTH LOS ANGELES (CBSLA) — Federal agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives Thursday began surveying the damage and reconstructing what led to a Wednesday evening explosion in South Los Angeles that injured 17 people.

“I can’t speak for the entire nation, but I’ve never seen that before,” Ginger Colbrun, an ATF special agent, said. “And I’ve been working for ATF for over a decade.”

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The explosion of a Los Angeles Police Department truck, caused after a planned police detonation of seized illegal fireworks, happened at about 7:40 p.m. at East 27th and San Pedro streets.

Nine LAPD officers and one ATF officer were taken to nearby hospitals, along with six civilians. A tenth LAPD officer was hurt, but was not hospitalized, according to the L.A. Fire Department.

June 30, 20201. (CBSLA)

Names of the injured were not immediately released. Those hospitalized included 11 men and five women, all ranging in age between 42 and 85, according to LAFD.

In a news conference early Thursday morning, the LAPD described all the injuries as mild to moderate in nature.

The explosion occurred after the LAPD had seized over 5,000 pounds of illegal fireworks from a nearby home. A 27-year-old man was also arrested.

Ten pounds of the illegal fireworks were placed in a specialized armored truck designed for controlled detonations.

However, what was supposed to be a controlled detonation turned into a massive explosion. The explosion flipped cars and shattered windows across a two-block radius. There’s no word on exactly how many homes were damaged. About 12 homes are under mandatory evacuation.

A Los Angeles police official confirmed Thursday that some residents were not evacuated prior to the preplanned detonation.

“Officers went door-to-door,” LAPD. Lt. Raul Jovel told CBSLA. “After the explosion, they discovered that some folks were still in the vicinity that did not answer the door. And that’s how we discovered that some folks were injured.”

The boxes of illegal fireworks prior to a detonation gone wrong. June 30, 2021. (LAPD)

Reporters on the scene said immediately before the explosion, officers moved them away from the vehicle and yelled, “Fire in the hole,” multiple times.

“When we got over the scene here, we were kind of expecting just some routine thing and to kind of get the shot that was gonna be the bookend to this story of basically this armored canister probably shaking a little bit and smoke coming out at the end of it,” Sky9 reporter Desmond Shaw said. “And then it just went catastrophically wrong. After it happened, we felt the blast up here, and it just kind of shook up my head a little bit.”

Neighbors described the explosion as “a really hard earthquake.”

As of Thursday morning, a large area around the explosion site was blocked off.

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“Throughout the night, we did a sweep of the surrounding blocks to make sure there were no devices that were hazardous to the community members here,” LAPD Lt. Raul Jovel told reporters early Thursday morning.

Earlier in the day Wednesday, the LAPD said officers received a tip that there were illegal fireworks being stored at a home in the 700 block of 27th Street. When officers arrived, they found approximately 5,000 pounds of  “commercial-grade fireworks,” LAPD Chief Michel Moore said.

Bomb squad technicians and investigators arrived on scene to remove the fireworks from the home, loading pallets full of explosives into multiple large vehicles in the alleyway behind the home where they were driven to an off-site location for eventual destruction.

June 30, 2021. (CBSLA)

Officers also found what Moore described as “improvised explosive devices,” that were loaded into the containment vessel for detonation. Moore said that by the bomb tech’s estimation, the vessel should have been able to safely dispose of the devices.

However, when officers detonated the explosives, Moore said a “catastrophic” failure occurred, leading to the explosion.

Law enforcement sources told CBSLA that the top of the armored container device, which can weigh as much as one ton, was blasted two blocks to the east and smashed part of a roof before landing in the dirt behind the home.

Moore alleged that the officers followed the necessary protocols, but “something happened in that containment vehicle that should not have happened, and we don’t know why, but we intend to find out why.” The truck is capable of handling up to 15 pounds of IEDs. There were 10 pounds at the time of the explosion.

The LAPD Thursday was waiting for national ATF teams to arrive and help assist with the investigation.

Meanwhile, Moore said 27-year-old Arturo Ceja was taken into custody at the home on suspicion of possession of destructive devices. According to authorities, Ceja acquired the fireworks out of state with plans to sell them to residents in the neighborhood for the July 4th holiday.

June 30, 2021. (CBSLA)

Moore also said a 10-year-old child, identified as Ceja’s brother, was found at the home and was taken into protective custody. He said the Department of Children and Family Services was investigating.

Ceja was being held on $500,000 bail, Moore said.

The Red Cross has set up a long-term shelter at Trinity Recreation Center for residents of the approximately 12 homes who have been displaced by the street closures. Those closures could last through the weekend, police said. Seven residents stayed at the shelter overnight Wednesday.

The Martinez family is among those staying at the shelter. Jovana Martinez and her brother Jafet were pulling into the alley behind their apartment when the explosion occurred.

“All our windows are broken, from my bedroom to my brother’s room, everything was shattered,” evacuee Jovana Martinez said.

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“Honestly, I don’t know what went so wrong that a whole armed vehicle that is meant to withstand bombs got destroyed into pieces,” Jafet Martinez added.