A South Carolina 3-year-old who was trapped in a hot car has died, medical officials said Sunday.

Logan Cox of Lancaster County suffered severe heat stroke Wednesday after climbing into a car when his parents did not see him.

The boy’s mother said her son’s death is something she will have to live with forever. She wants people to know it was a tragic accident.

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Logan’s grandmother said last week that the family was taking a nap when Logan woke up, wandered out of the house and got into the family’s car with their pet dog.

The mother believes she was asleep for about 30 minutes when she woke up and ran outside to find her son.

The Department of Social Services is investigating. Family members reiterated this was an accident. They are now planning his funeral.

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Below is the original story by Greg Suskin of WSOC-TV – Charlotte, N.C.:

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Original story: Teresa Clevinger was in tears Thursday as she talked to WSOC-TV about the horror of what happened to her 3-year-old grandson, Logan Cox.

"I just want my grandson back. I just want my grandson home," Clevinger said.

On Wednesday afternoon, Clevingers said the boy woke up from a nap and walked outside her home on Walnut Road while his parents were napping.

The boy and a dog got into his mother's car and shut the door, then could not get back out, Clevinger said.

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"This was an accident. It has never happened before and it'll never happen again," Clevinger said.

In the 911 call obtained by WSOC-TV, Clevinger can be heard telling the dispatcher she didn't know how long the boy had been outside in the car.

During the call, his parents had him in the bathtub putting cold water on him, trying to bring his temperature down.

The dispatcher asked if they had a thermometer in the home to take his temperature. Clevinger replied that they did not.

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On Thursday, Clevinger told WSOC-TV the child was in the car for about 30 minutes.

The boy's mother fell asleep on the couch and didn't know he was gone, Clevinger said.

"She was looking for him because she didn't see him in the house and she was hollering for him, and he didn't answer her," she said.

Then the boy's mother noticed the blinkers flashing on her car and found the boy slumped over inside it, Clevinger said.

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The dog that jumped into the car with the boy was dead.

A Lancaster County sheriff's detective and a Department of Social Services case agent spoke with the boy's parents on Wednesday night.

Clevinger told WSOC-TV that the parents parents have not left  the child's side at the hospital.

Thursday afternoon, hospital officials said the boy was still in critical condition.