A mother left her 5-year-old son in a parked Mercedes with the windows rolled up while she shopped at a Walmart on a sweltering South Florida afternoon, police said.

The boy, who was desperately knocking on the car window to get the attention of passersby, was eventually freed by Walmart employees, the police report said.

Martine Louis-Jacques, 62, was charged with child neglect without serious bodily harm and appeared in court Tuesday, NBC 6 South Florida reported.

Police said the boy, whose identity has not been released, was “frightened and distressed” after being left in the car for about 20 minutes while his mother shopped at the Pembroke Pines store.

“Walmart employees observed the child (redacted) unsupervised in the vehicle, which was completely locked with the windows rolled up,” it said.

Martine Louis-Jacques, 62, of Miramar, was arrested Monday after leaving her son in her hot Mercedes while she shopped at Walmart for 20 minutes

A passerby in the parking lot alerted a Walmart employee to the situation, and store employees eventually freed the boy by instructing him to unlock the car from the inside.

After employees brought the boy into the store, he ran to his mother, police said. The two left the store without speaking to employees and before police arrived.

The Miramar resident was arrested at her home after police used video surveillance to identify her car and determine her address.

The child was freed from the car after attracting the attention of a passerby

She was taken to the Broward Sheriff’s Office Main Jail and her bail was set at $3,500.

According to the advocacy group Kids and Car Safety, about 40 children die of heat stroke because they are trapped in hot cars.

More than 1,000 children have died in such incidents over the past three decades.