Two young cousins from Missouri were live-streaming on Instagram during a family party when one fatally shot the other before shooting herself.

According to the St. Louis Post-Dispatch, the family members of Kuaron Harvey, 14, and his younger cousin, Paris Harvey, 12, believe the deaths were an accident.

Susan Dyson, the cousins’ grandmother, said her two grandchildren were raised together and were more like siblings than cousins. She also revealed that she saw the viral video, and although they shouldn’t have been playing with the gun, it just went off.

“It wasn’t a situation where they were arguing or anything like that. They were playing with the gun when they shouldn’t have been,” Dyson said. “Of course, they shouldn’t have been doing it. I think it just went off. It went off by mistake.”