(Reuters) - Three Mississippi teenagers face capital murder charges in the death of a 6-year-old boy who was found dead in his mother’s car on Thursday after it was stolen from a grocery store parking lot while he slept inside it, police said.

The child, Kingston Frazier, was in a Toyota Camry at about 1:15 a.m. CDT (0615 GMT) outside a Kroger store in Jackson while his mother was inside. A Honda Civic drove up and a passenger got out and jumped into the Camry before both cars sped off, Jackson Police Commander Tyree Jones said.

Police found the kidnapped boy dead in the back of the abandoned Camry about eight hours later on a rural Madison County road about 10 miles from the store. He had been shot at least once, Jones said by telephone.

Kingston was scheduled to graduate from first grade on Thursday, according to the boy’s uncle, Martin Archie.

“He was so excited that was all he was talking about yesterday was his graduation today,” Archie told Jackson CBS affiliate WJTV.

Three youths - Byron McBride, 19, and DeAllen Washington, 17, both of Jackson, and Dwan Wakefield, 17, of Ridgeland - were arrested and are being charged with capital murder, said Warren Strain, a spokesman for the Mississippi State Police.

He had no details on a motive, adding, “A 6-year-old kid, who does that?”

Jones said the incident was caught on surveillance video, and the Honda also had been found. An alert was put out for the missing child, and relatives told WJTV they had combed the city looking for Kingston.

“This is the worst thing,” a sobbing Deanna Moore, Kingston’s aunt, told WJTV as family members wept behind her.