At the age of six, Nahla the dog wasn't exactly elderly, nor was she sick. Her sudden and heartbreaking death was the subject of a viral TikTok that had users desperate for answers.

On the way to his lake house in Maine with Nahla and another pooch – two-year-old Sam – Johnny Hilbrant shot a harmless video of the Golden Retriever.

Nahla looked happy as she leaned out of the car window – but according to the captions, she'd end up dead just 90 seconds later.

The video even features a photo in showing the lifeless dog on Hilbrant's lap.

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The clip taken last year left TikTok users desperate for an answer to the shocking mystery, since the post did not feature an explanation.

In an interview with People, Hilbrant finally provided one.

Hilbrant said that he parked his car outside the destination just a minute after the picture was taken.

His father-in-law, who was standing outside the home, and Nahla ran excitedly to him.

"After greeting him, she did a 180 and sprinted across the driveway," Hilbrant told People.

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"Instead of running in a straight line, she veered to the right about a foot and into the back of our car. She hit her head with extreme force on the steel tailpipe of our car."

Nahla only got up once more briefly and then collapsed after a seizure.

"We knew instantly that she was gone," Hilbrant said.

"The next several minutes were a complete horror as we were helpless and knew we could not help Nahla."

Hilbrant still doesn't know why the golden retriever ran into the car. He suspects that she may have been suffering a heart attack, or maybe just misjudged the situation and lost her footing.

"It was one of the most horrific things I have ever witnessed in person," the still grief-stricken dog owner recalled.