The death of a 3-year-old boy left inside a parked car outside a day care center in Warner Robins was caused by heat stroke, and state officials are investigating the unlicensed in-home daycare, authorities said Tuesday.

Stacey Moore with the Georgia Department of Early Care and Learning said the Sister-n-Sister Family Home Day Care center could be ordered to shut down once the probe is complete.

Authorities say Andrew Calloway died Sunday after he was found unresponsive in a car parked outside the daycare center. Warner Robins police spokeswoman Tabitha Pugh said the child died of heat stroke.

Pugh said the center is run by 50-year-old Shelia Henderson and her 66-year-old sister, Johnnie Mae Grayer. Neither could be reached for comment Tuesday, and state and local officials said they were unable to get anyone at the daycare center to answer the door.

Pugh said Henderson had a business license with the city.

"It's my understanding she was trying to get a state license," Pugh said.

Pugh said Andrew was one of three children in the care of the center that day. The others included the boy's 1-year-old cousin and Henderson's 10-year-old niece, who were not harmed.

She said Henderson and Grayer returned from lunch about 4:15 p.m. with the three children and went inside the home. Pugh said they realized about an hour and a half later that Andrew was still in the car.

Moore said if the program doesn't shut down, the state could ask the attorney general to seek an injunction to close it. She declined further comment because the state investigation is ongoing.

Neither Henderson nor Grayer has been charged in the case, but police are also investigating.

The boy's father, 26-year-old Andrew Calloway, told The Telegraph of Macon that he didn't know about what happened until he arrived to pick up his son at 6:30 p.m., only to find the home roped off by yellow crime scene tape. He described his son as "full of energy, very smart and handsome."

"There was no excuse for my son being left in a locked car," Calloway told the newspaper.

In a separate case involving a toddler’s death under similar circumstances in Clayton County, a juvenile court judge on Monday ordered a 16-year-old worker at a Jonesboro day care center to create a memorial on behalf of the dead girl.

The teen, whose name was withheld because she is a juvenile, also was sentenced to two years’ probation and 40 hours of community service for her part in the death of 2-year-old Jazmin Green.

The little girl died June 20 after being left alone for about two hours in a hot van at Marlo’s Magnificent Early Learning Center following a field trip.

The teenager, the day care’s owner and the owner’s daughter were charged with cruelty to children in the second degree, reckless conduct and involuntary manslaughter.

The toddler’s death came several months after the facility was found to have violated a state law that requires a vehicle check after field trips to ensure children have been removed safely.

The day care center’s owner, Marlo Maria Fallings, and her daughter, Quantabia Shantell Hopkins, are out on bond awaiting a court date. The facility remains closed.

-- Staff writer Tammy Joyner and the Associated Press contributed to this article.