A 13-year-old boy and his older brother were killed Tuesday evening in a suspected fireworks blast that sent shock waves through a Bell Gardens neighborhood, investigators said.

Officials on Thursday said they suspect someone in the apartment was making fireworks at home when the deadly explosion took place. Inside the rubble, investigators discovered large pipes and energetic powder, similar to what is used in fireworks and pyrotechnics, Lt. Michael Modica of the Los Angeles County Sheriff’s Department said.

“The whole top of the roof is blown off,” Modica said.

Neighbor Lorena Ramirez said she was doing homework in bed about 6 p.m. Tuesday when she felt the ground shake.

“It felt like a shock wave went through me,” Ramirez said. “I immediately went outside, and all of my neighbors were already standing there, looking up across the street. It was like a pillar of fire over the rooftops.”

Bell Gardens Police Department responded to the 6500 block of Purdy Avenue, according to a Sheriff’s Department news release.

Sheriff’s arson investigators found materials used to create homemade fireworks and explosives at the scene, according to the release.

Neighbors told The Times they have constantly heard fireworks going off in the area, even though they are illegal in the city. On Thursday, standing outside the home where the blast originated, Bell Gardens Police Chief Paul Camacho said the explosion was the consequence of people ignoring the law.

“We continue to let the public know that fireworks are dangerous,” Camacho said. “When people are just not using common sense, that’s the type of thing that could happen.”

On Thursday morning, fire department trucks were tearing down the affected side of the building, which was entirely blackened and hollowed out from the flames.

Candles along and flowers on a fence surrounding a yard.

A sidewalk memorial for 13-year-old Carlos Abraham Hernandez, who was killed along with his older brother Christopher Benitez, 24, in what authorities believe was a fireworks explosion, on Purdy Avenue in Bell Gardenson Thursday.

(Myung J. Chun/Los Angeles Times)

Christopher Benitez, 24, was found with burns on about 90% of his body and died Thursday just after midnight, Modica said. Thirteen-year-old Carlos Abraham Hernandez was found dead in the apartment.

A 11-year-old suffered minor injuries, Modica said.

Investigators are still processing the scene and investigating the materials that were found inside, including whether they may have been mixed with other substances, but Modica said investigators believe the energetic powder sparked the explosion.

Modica said that it is unclear how much was in the apartment at the time, but that it “must have been a significant amount” because of the explosion. It was yet unclear what the powder was, and whether it was legal to be kept in the home.

“People just don’t understand how dangerous this stuff can be,” Camacho said.

Ramirez said neighbors gathered around waiting for ambulances to arrive, even as they heard screams coming from inside the building.

“It sounded like a young man,” Ramirez said, tears welling. “He was screaming, screaming in pain. I never thought I would hear anything like that.”

Across the street, Concepción Calderón said the rattle that shook her home was so intense that she mistook it for an earthquake.

“But I knew it couldn’t be,” Calderón said in Spanish. “Because at the same time, I hear this ‘boom’ like a bomb, and the windows rattled.”

As she looked at the inferno, Calderón said, she saw a boy whom she baby-sits limping, showing that he had burned his foot.

“He looked at me and said, ‘Look at my foot. I won’t be able to play soccer now,’” Calderón said.

Benitez was a member of the National Guard and a student, according to a GoFundMe page for funeral expenses.

Neighbor Ramona Venegas describes Carlos as a quiet but playful young boy, who loved to play soccer and would often kick balls into her and neighbors’ yards and politely asked that they tossed them back out.

She said Benitez loved his three dogs and walked them often around the neighborhood.

“We’re all still recovering and I’m especially praying for their mother,” Venegas said. “It’s such a terrible loss.”