BLACK JACK, Mo. (AP) — A house explosion near St. Louis early Friday that killed two people and critically injured several other people might have been caused by explosives used to make fireworks, authorities said.

The explosion at around 1:20 a.m. destroyed a home near the town of Black Jack. The blast was so powerful that it shook other homes and blew out neighbors’ windows, sending debris more than a block away.

Christopher Jones, 17, was one of the two people who were killed in the blast, the St. Louis County Medical Examiner’s office told the St. Louis Post-Dispatch. St. Louis County police said Friday afternoon that a second person was found dead at the scene. That victim’s name and age were not immediately released.

Four others were taken to a hospital with life-threatening injuries. Their names and ages were not released.

The local fire chief, Ankeneth Corbin, told the Post-Dispatch that young people were in the garage making fireworks with explosives.

“If you buy 50 pounds of any explosive, you have just created a bomb,” Corbin said. “The ATF found numerous boxes (of materials) they had ordered online. Electrostatic, anything, can cause a spark.”

Neighbor Nichole Thomas described the scene as “pure chaos.” She said she saw flames engulfing the home and a young boy and others running frantically.

Investigators with the regional bomb and arson squad spent the morning seeking clues in the rubble. The brick home’s garage was leveled and the home itself was a burned-out shell with partial walls standing.