The presence of carbon monoxide was confirmed in a parked vehicle in Toledo, Ohio, where five people were found unresponsive and three of them died Wednesday in what an official described as an accident.

The Ford Explorer had pulled over with a flat tire into a parking lot, and the victims were discovered shortly after 11 a.m., Toledo Fire Chief Allison Armstrong said.

City of Toledo spokesperson Rachel Hart said the victims included a grandmother and her grandchildren. She said the woman’s son who had been called to help found the bodies.

Mayor Wade Kapszukiewicz said foul play was not suspected. He said three of the victims died while two children were hospitalized in critical condition. Their names, ages and hometowns weren’t immediately released.

“Today, a family experienced a tragedy that no family should ever have to endure,” the mayor said on Facebook.

Investigators later started the vehicle with the doors closed and a meter inside. In a telephone interview, Armstrong said, “we had a high spike of carbon monoxide inside the passenger compartment on that vehicle.”

She said the vehicle was towed by police.

“They’re going to have to do some further investigation to see if they can identify how does that happen,” she said. “I think that’s an important piece of this that people want to know, and they should know for everybody’s safety.”

Armstrong recalled a “very similar” incident several years ago involving carbon monoxide that seeped into holes in the floorboards of a vehicle.

Ford Explorers were part of a previous six-year investigation by the federal government into exhaust odors in passenger cabins.

In 2023, the National Highway Traffic Safety Administration says it reviewed more than 6,500 consumer complaints, tested SUVs in the field and called in automotive, medical, environmental health and occupational safety experts before determining that the SUVs didn’t have high levels of carbon monoxide and didn’t need to be recalled.

The probe covered nearly 1.5 million Explorers from the 2011 to 2017 model years.

Armstrong said it wasn’t immediately known what year the SUV involved in Wednesday’s incident was made.

John Raby, The Associated Press