A mother was arrested on Friday after her two children were found dead in a car that was lit on fire in San Antonio.

Subscribe to read this story ad-free

Get unlimited access to ad-free articles and exclusive content.

Marlene Vidal, 34, of Edinburgh, Texas was charged with capital murder after the bodies of her children — ages 5 and 7 — were discovered in an engulfed vehicle in a warehouse parking lot, according to police.

San Antonio Police Assistant Chief Jesus Salame said at a press conference that a passerby walking his dog called 911 on Friday morning to report the burning vehicle.

Salame said Vidal had told the passerby she had already contacted police, though it is unclear whether that was true.

After firefighters extinguished the fire, they discovered two children inside the vehicle, according to Salame.

It remains unclear if the children were dead before or after the car was set on fire. A local medical examiner is still investigating the cause of death.

Surveillance footage and statements Vidal made to police indicate she “was solely responsible for the death of these two children,” according to Salame.

Authorities have not established a motive, though Salame noted “there are indications that mental health issues may have played a role.”

“I know our community is going to be hurting right now,” he said. “Everyone’s going to want to know why something like this happened, and unfortunately, the why is sometimes the hardest question to answer.”