Police did not release specific details about the confrontation, WTTG said, but added that the teen was shot multiple times, and there was no indication he was armed.
The station said there's no indication of who placed the 911 call reporting the incident, but investigators said arriving officers found the homeowner performing CPR on the teen, who was taken to a hospital and later pronounced dead.
Investigators added that the homeowner is cooperating with authorities, and that the gun used in the shooting is legally registered, WTTG reported.
Police also found a car on Quincy Street that had been reported stolen, and cops believe the 13-year-old used it, the station said.
Investigators believe two other juveniles also were involved in the incident, WTTG said, adding that a neighbor in the area said those two juveniles tried fleeing the scene in a vehicle before bailing out in an alley and running off.
Will the homeowner be charged?
Authorities are working to determine if any criminal charges are warranted against the homeowner, the station said.
WTTG said in a separate story that officials are working with the U.S. Attorney's Office to determine if there will be charges.
The station noted that the community calls for transparency and accountability are growing louder.
"I'm at a loss for words as to what would possess a resident to take matters into their own hands and take the life of a young person," Ward 5 council member Zachary Parker — who's been in office for a week — told WTTG.
Parker remarked to the station "how little information is being released about the person that took Karon's life," and that he's joining with neighbors and calling on police to release information and hold the individual accountable.
Parker added to the Washington Post that he has “deep concerns about neighbors taking justice into their own hands" and that "our young people deserve long lives with the opportunity to dream big. Healthy communities are safe communities, where we all work together to care for one another and invest in everyone’s well-being.”
D.C. council member Christina Henderson tweeted that she would check in with D.C. Public Schools and the Department of Behavioral Health to ensure that Brookland Middle School — where Karon attended — has proper support, WRC-TV reported.
"Property is not greater than life. Karon should be alive today," Henderson tweeted.
The middle school's principal in an email to parents described Karon as a quiet and inquisitive sixth grader who loved football and fashion and said he leaves behind his mother and three sisters, WTTG said.
Brookland Middle School was to honor Karon's life Monday, the station added, and mental health services will be available for both staff and students this week.