South Los Angeles residents grapple with damage left in wake of fireworks blast

SOUTH LOS ANGELES (KABC) -- Shell-shocked residents are still assessing the scale of the damage to their homes after a massive explosion Wednesday rocked their South Los Angeles neighborhood in what was supposed to be a safe operation to destroy a cache of illegal fireworks.

It could take days to determine why the material exploded inside a spherical containment vessel on a tractor-trailer, tearing the rig apart. The explosion was heard blocks away and left 17 people injured, including several LAPD officers.

For Endy Garcia, it was a frightening experience. She was at home with several family members when she heard a huge explosion and seconds later something struck the house. It turned out to be the door to the iron containment vessel being used by the bomb squad.

"It was really strong. It was a strong impact. I felt like the houses were gonna fall," Garcia said.

RELATED: South LA fireworks explosion occurred after 'catastrophic failure' during planned detonation

What was supposed to be a safe operation to destroy a cache of illegal fireworks turned into a "total, catastrophic failure" of a LAPD bomb squad vehicle, leading to a huge explosion in South L.A., authorities say.

The circular object knocked out a chunk of the roof and damaged a tree before landing in the backyard.

Garcia's home is blocks from the site of Wednesday's massive explosion, which happened while LAPD officers were trying to safely detonate illegal fireworks.

The heavy object thrown into Garcia's yard by the blast also slammed into the wall of her aunt's room.

"One of the officers even told her 'You're lucky it didn't go through because it could have killed you,'" she said.

WATCH: South LA fireworks explosion: Students of nearby school react to blast

In the wake of a massive explosion during a planned detonation of illegal fireworks in South L.A., some students of a nearby elementary school say they're on edge.

Video showed extensive damage inside two neighboring homes on East 27th Street, just feet from the site of the explosion.

Members of the Reyes and Ruiz families say shutters were blown out. Walls were damaged and broken glass covered floors.

A relative describing the terrifying ordeal says a ceiling fell on her father and glass shards hit her mother.

Both were transported to the hospital for treatment.

Some residents were standing nearby when the container exploded.

An investigation is ongoing as a large portion of the neighborhood remains shut down.

The Associated Press contributed to this report.