A one-year-old is dead after being left in a hot car for hours while his mother underwent a cosmetic procedure, police said.

Maya Hernandez, 20, is facing charges of involuntary manslaughter and child cruelty after allegedly leaving her two sons, Amillio Gutierrez, 1, and his two-year-old brother, locked inside a parked car as temperatures soared to 101 degrees in Bakersfield, California on June 29.

According to police, Hernandez had called a local med spa earlier that morning to ask whether she could bring her children inside. A staff member told her, “Sure, if you don’t mind them waiting in the waiting room, hun,” according to local ABC affiliate KERO.

But instead of bringing them inside, authorities say, Hernandez left both boys strapped into their car seats with the vehicle locked while she filled out paperwork and underwent a lip filler procedure.

Though the procedure itself reportedly lasted only 15 to 20 minutes, employees told police the spa was busy that day and Hernandez was away from her car for about two and a half hours. She reportedly never checked on her children during this time.

When Hernandez returned to the car around 4:30 p.m., she found Amillio foaming at the mouth and suffering what appeared to be a seizure. Employees at the med spa rushed outside to help, bringing the older child inside to cool him with water.

Amillio, whose body temperature reached 107 degrees, was transported to a hospital where he was pronounced dead at 5:48 p.m. His brother survived and was placed in child protective custody.

Hernandez later told officers she believed the boys would be safe because she left the air conditioning running.

However, her 2022 Toyota Corolla hybrid is equipped with an automatic shut-off feature that turns the engine off after one hour, according to an expert cited in the criminal complaint, obtained by Law & Crime.

By the time officers arrived at 4:45 p.m., the interior of the car was warm. Police estimate the children were left without air conditioning for at least 90 minutes.

The boys’ grandmother, Katie Martinez, is heartbroken.

“They were strapped in their car seats. They couldn’t even get up to save themselves,” she told ABC7. “She literally locked them in their car seats and shut their doors.”

The criminal complaint states that when Hernandez was informed of her son’s death, she “admitted that she knew it was irresponsible to leave her kids in the car” and “thought about it when she got out of the car but had no justification as to why she left them anyway.”

Despite the charges, Martinez described her daughter as a loving mother.

“She wasn’t like that. She was a really loving mom,” she said. “Those boys loved her. They relied on her.”

A GoFundMe page notes that the boys’ father is currently incarcerated. He learned of Amillio’s death from a jail chaplain the following day, according to KFSN.

A vigil was held Saturday at a local park in Amillio’s memory.

Hernandez remains in custody on more than $1 million bail. She is scheduled to appear in court on July 14.