MIAMI -- The mother of an 18-month-old boy who died after he was left strapped in the family's car while his mother went to work Thursday was arrested and charged with aggravated manslaughter of a child, the State Attorney’s Office said.

"We try to balance what the law says," said State Attorney Kathy Fernandez-Rundle. "Every caregiver, parent, anyone over a child has a standard of care for that child."

Prosecutors decided that standard of care was legally breached in the backseat of a Toyota Thursday when 39-year-old Elizabeth Cuesta, the mother of two children, dropped her 6-year-old son at school and went to work at the Banfield Pet hospital on Flagler Street and 82nd Avenue, leaving her 18-month-old in the car.

Banfield released the following statement Friday: "We are devastated by the news that a young child passed away while left unattended in a parked car. We are in the process of gathering additional information and are working with local authorities as they handle the situation.”

In her statement to detectives, Cuesta said she forgot her son was still strapped in his car seat in the back of the family’s silver Toyota Tundra when she went to work.

At around 3 p.m., the child's father found his son in the car when he arrived to meet his wife for lunch -- six hours after the boy's mother had left him inside the vehicle, police said.

He immediately called 911. When paramedics arrived, the man carried his lifeless boy from the hot truck to the waiting ambulance. But there was nothing paramedics could do.

Midday temperatures Thursday hovered in the 80’s.

"Clearly she violated the law," Fernandez-Rundle said. "We all know that a baby -- any live object -- in a car in South Florida is in an oven in 20 minutes.

The signs that Cuesta is a caring parent were all there, Local 10's Glenna Milberg reported. Sunshields were placed on the car windows and the baby was in an appropriate car seat.

But the mother who may have simply made a heartbreaking mistake now faces manslaughter charges.

"If for any reason you are negligent and it results in an injury or death, it's a manslaughter case," Fernandez-Rundle said. "Is she a threat to the community? Probably not. Is there any sentence we can give her that is going to be worse than the life sentence she has now? Clearly not."