By the time first responders arrived at the home in Amarillo, Tex., early Monday, one child inside was already unconscious.
Other members of the household were sick and disoriented. Firefighters used CPR to attempt to revive the unresponsive child but could not.
Six people were rushed to a hospital, where three more children from the home would later die, officials said.
The culprit was not what they thought at first.
“They initially thought this was going to be carbon monoxide,” Amarillo police spokesman Jeb Hilton told The Washington Post in a phone call Tuesday morning. But interviews with family members — as well as a distinct odor in the home — ruled out the colorless and odorless gas, he said.
Instead, investigators concluded that someone had used a professional-grade pesticide containing aluminum phosphide under the home.
At some point, a family member tried washing the chemical from underneath the house with water, according to an Amarillo Fire Department statement.
The combination of water and aluminum phosphide creates phosphine, a gas that can cause fluid to accumulate in the lungs and cardiac arrest if inhaled, according to the Centers for Disease Control and Prevention.
Officials said they believe it was exposure to this gas that sickened the family and ultimately killed four of its children.
“It’s a very lethal chemical,” Amarillo fire spokesman Larry Davis told the Amarillo Globe-News. “It causes pulmonary edema and basically the lungs fill up with fluid. We don’t know that that’s the cause of death so far, but that’s one of the more severe symptoms. It took us a long time to identify the chemicals.”
Potter County Justice of the Peace Gary Jackson identified the deceased children as 17-year-old Yasmeen Balderas, 11-year-old Josue Balderas, 9-year-old Johnnie Balderas and 7-year-old Felipe Balderas.
Jackson identified the parents as Pedro and Martha Balderas. As of Tuesday morning, Pedro Balderas and four unidentified children were in stable condition at a hospital in Amarillo, he said.
Martha Balderas was airlifted to University Medical Center in Lubbock, according to ABC 7 News. A spokesman for the hospital in Lubbock told The Post that Martha Balderas remained in critical condition Tuesday morning.
Jackson told The Post that autopsies are pending and toxicology reports would probably take an additional three to four weeks.
Terry Rodriguez, who identified herself as an ESL teacher at Eastridge Elementary School, where some of the Balderas children attended, set up a GoFundMe account to raise money for the family.
“The Balderas family is heartbroken today,” Rodriguez wrote. “They have lost four members of their family.”
On the page, she described the oldest, Yasmeen, as a senior at Palo Duro High School who had been looking forward to graduation. The other three children were her students, Rodriguez wrote.
“Josue wanted to be a priest and was an [altar] server at St. Lawrence. He was a gentle soul, slow to anger and quick to provide comfort,” she wrote. “Johnny was a comic. So smart and so aware of his strengths and weaknesses. He was the first to laugh at himself and never met a stranger who wasn’t just a friend in the making. Felipe was my most recent student. He was everyone’s friend and so proud of all the progress he made daily.”
Neighbors told the Amarillo Globe-News they had seen the children playing outside over the past couple of days and that the boisterous family kept the neighborhood “alive.”
“They’re a good family,” one neighbor, James Compton, told the newspaper. “They were very family-oriented and took care of their family. The whole family is friendly. It just hasn’t sunk in what’s happened.”
Compton told The Post on Tuesday that no other houses on the street seemed to have been affected and that they were not evacuated.
Another neighbor, Dan Dibala, said Pedro Balderas had asked him recently about getting a cat for a rodent problem they were having at the home — which likely led to his decision to use the pesticide.
“There aren’t words to describe it,” an emotional Dibala told the Amarillo paper.
Police do not know how long the family had been exposed to phosphine and are treating the incident as an accidental poisoning with no criminal intent, the fire department said in a statement.
Although some local media outlets specified a pesticide brand, Hilton said Tuesday that it was unclear what type of fumigant was used.
“I know it’s hard to get a hold of,” Hilton said. “It’s not something that the normal citizen could get their hands on. It’s something that a licensed pest-control person would have.”
Several first responders were taken to the hospital as a precaution Monday, but no other people were injured, police said.
The department’s special crimes unit was still investigating the scene Tuesday, he said.
“We have to determine what do we need to do to make this house safe for people to live in again,” Hilton said.