BELL GARDENS, Calif. (KABC) — A second person has died following a massive explosion at a Bell Gardens apartment building earlier this week.

Christopher Benitez, 24, died at the hospital Thursday just after midnight, according to investigators. He suffered serious burns throughout most of his body.

Benitez is the older brother of 13-year-old Carlos Hernandez, whose body was discovered in the rubble on Wednesday.

Another boy, an 11-year-old, was rescued from the building. He suffered minor injuries and has since been released from the hospital.

Explosion may have been caused by homemade explosives

Investigators believe the brothers were assembling a homemade firework or explosive device when the blast occurred, said LASD Lt. Michael Modica during at a news conference outside the apartment building.

“What we do know and what we do suspect is an energetic powder that was used to create the massive explosion,” said Modica.

“If you put them on a plate and lit them … they would just fizz or make a light or a small explosion. If you take them and you contain them in something, then that creates pressure which then would create an explosion,” he added.

Meantime, anyone with information about the explosion was urged to contact the sheriff’s Arson Explosives Detail at 323-881-7500.

“People just don’t understand how dangerous this stuff can be, and I think as a result of what we see behind us … that is the consequences of not following the laws and not really kind of … doing what you’re supposed to do,” said Bell Gardens Police Chief Paul Camacho.