A Louisiana grandmother allegedly knocked down and killed her 5-year-old grandson while driving drunk to work at 7 a.m., according to authorities who called it “any parent’s worst nightmare.”

Kristen Anders, 55, was pulling out of her driveway in her 2016 GMC Yukon in Slidell early Tuesday when she struck grandson Carson Lawson headfirst as he waited for his school bus, killing him, police said.

“It’s safe to say that I don’t think anybody believes that she knew the child was in front of her car,” Police Chief Daniel Seuzeneau said at a press conference later that day.

However, the grandmother was allegedly under the influence of alcohol and sedatives and was arrested at the scene for vehicular homicide, police said.

“This is any parent’s worst nightmare,” the police chief said.

“I just want everybody to understand that this is a very tragic situation for this family, because not only did they lose their precious 5-year-old child, they’re also having to deal with the fact that the grandmother is now under arrest for this incident,” Seuzeneau said.

“I was at the scene this morning, as well as several of our officers. This affects everyone. This hits home hard for all of us and all of the first responders who were at that scene.”

Anders stopped immediately after realizing what had happened outside her home, some 28 miles northeast of New Orleans, cops said.

She has been cooperating with the investigation.

An autopsy is scheduled later this week for Carson, who turned 5 in June, the coroner’s office said.

The investigation is ongoing.