ST LOUIS, United States — Two young cousins, 12 and 14, were live streaming from a St Louis apartment when one child fatally shot the other before killing herself in what family members say was a tragic accident.

Police are still investigating Friday’s incident in which a 12-year-old girl, Paris Harvey, shot a 14-year-old boy, Kuaron Harvey, before shooting herself.

The cousins were alone in the bathroom making a video in the mirror when the incident happened. In the video, Paris points the gun at Kuaron’s head before it goes off. In a panic, as she reached for her cousin and the gun, she goes out of frame and the gun goes off a second time.

Both children received head shots.

Police initially described it as a murder-suicide, but the family have labelled it a freak accident.

According to a FOX news report, Susan Dyson, the girls’ grandmother, told the St Louis Post-Dispatch that she saw the Instagram Live video the two cousins were making together at a downtown St Louis apartment the family had rented to celebrate March birthdays.

She reported that they weren’t arguing but were playing with the gun “when they shouldn’t have been” and “it went off by mistake”.

The family reported that the cousins had been raised together. They often made videos together and played pranks.