JONESBORO, Ga. -- Clayton County Police released many new details Tuesday about what they believe led to a home invasion that left two children dead.

Daveon Coates, 15, and his sister, 11-year-old Tatiyana Coates, were gunned down early Saturday in an apparent home invasion. Police said no parents were home when the shooting occurred, and that a young child called 911 to report the invasion.

In a Tuesday afternoon news conference, Clayton County Police Chief Michael Register said that it appears the shooting were gang-related.

Register said that it appeared that the mother of Daveon and Tatityana allowed a family of six from Chattanooga, Tenn., to move into the home on Libby Lane. Sometime after their move, a 15-year-old in that family had gotten involved in gangs in the metro Atlanta area.

The shootings at the home early Saturday were related to the 15-year-old's gang activity, and that the two children who were killed were not the intended targets.

Register said that the 15-year-old allegedly involved in gang activity had fled to Chattanooga, but that he had been located and taken into custody on Tuesday afternoon.

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During the conference, Register called the case disturbing. "It disturbs me to my core," he said. "As a police officer and police chief, this disturbs me because this is the community that we are sworn to protect."

Back at the site of the murders, two women who didn't know either young teen or their mother were out setting up a memorial for Daveon and Tatiyana. Both have lost children to gun violence and said they know this mother's pain.

"I'm still fighting and I've been fighting," Tammy Parish told 11Alive's Chris Hopper. "November 20 for me will be five years, and it feels like yesterday."

While their gesture seems small, they said it's all they can do when the pain is so great. "It still hurts. I still cry. I mourn, I grieve."

"We are all connected now and we're all going to fight and do whatever it takes to stop this violence," Parish said.

Police are now questioning the 15-year-old, who they think might have valuable information about who the shooters might be.

If anyone else has any information about the incident, they're asked to call police.