There were tears and overwhelming sadness at a Cobb County elementary school Wednesday where the oldest of three children believed killed by their mother attended fifth grade.

Justin Medina, 10, died inside his south Cobb apartment, along with his 4-year-old brother and 9-month-old sister, according to police and Sanders Elementary School. As teachers and staff learned of the boy’s death, they shared the news with students, Principal Rebecca Jenkins said in a letter to parents.

“Justin was a delightful young man,” Jenkins wrote. “He was happy, friendly, and always had a kind word for others. We are deeply saddened by his passing and will miss him greatly.”

The American flag was at half-staff at the Austell school, located about two miles from where a family of four was found dead inside their south Cobb apartment. Grief counselors were on hand to help students and teachers.

Investigators believe Kisha S. Holmes, 35, killed her children and then herself inside a Walton Crossing apartment, but no information on a motive has been released. The bodies were found Tuesday morning by a maintenance worker at the complex, on Mulkey Road, which is near the East-West Connector and WellStar Cobb Hospital.

On Wednesday, Cobb police were awaiting autopsy findings to determine how the four died. An incident report released by police offered no additional details about the investigation.

Address records showed Holmes previously lived in Stone Mountain and had served in the military, but family members could not be reached.

At Sanders Elementary, students and parents were still shocked at the news and saddened by the loss. Robin Glover, a grandmother of a fifth grader at the school, told Channel 2 Action News she knew Justin.

“I just feel so sad,” Glover said. “I was praying last night for the family because whatever happens to adults, their problems, it’s not the children’s fault. And it hurts my heart to hurt a child.”