The adult supposed to be supervising them left to go to the store, police said.
Seven Virginia children have been hospitalized — three of them in serious condition — after one of them handed out sleeping pills to the group, police say.
All seven, aged between 1 and 7, were treated for overdose after a number of them were found unresponsive on Wednesday night.
According to Hopewell police, the mother of three of the children had dropped them off at the home of the mother of the other four, who was to babysit all seven.
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View StoryBut around 5 PM, the mom left the children to go to a corner store; when she returned she noticed the children "weren't acting right", but didn't think anything of it.
Then she noticed an empty prescription pill bottle — and called 911.
When first responders arrived, they found four of the children, aged one, two, three and four, unresponsive. The other three children were found elsewhere in the home, awake but lethargic, WTVR reported.
According to WRIC, the mother insisted to Hopewell PD that she told a man who was in the home that she was leaving, but admitted she may not have communicated clearly that he was supposed to watch the children; investigators have not confirmed if there was another man in the house at the time.
Police were initially unable to tell where the drugs came from, as the bottle was old and had its label rubbed off.
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View StoryBut after interviewing one of the seven-year-olds, they now believe the prescription sleeping pills were his, and that he somehow managed to get into the bottle before dishing them out to the other children.
"They were left unsupervised for a short period of time and one of the kids that have prescription medication got into it and shared with the other children here," Lt. Cheyenne Casale said.
Four of the older children are expected to make a full recovery, but the three younger ones were described as in serious condition.
"They are expected to recover, but because they don't know exactly how much of the prescription medication they ingested… so they are having a harder time processing and metabolizing [the drug]," police said.
Child Protective Services are now involved in the investigation, as police consider what — if any — criminal charges could be brought. The Commonwealth Attorney's Office has also been contacted.
"Find out who are we going to hold accountable and get these kids in a safe environment, that's our number one goal," Lt. Casale said.
Living conditions inside the home were described as "less than desirable," WTVR reported.