A 15-year-old boy was shot and killed by a teen playing with a gun before it discharged inside a northwest Aurora mobile home Sunday night.

At around 7:30 p.m., Aurora Police Department officers responded to a local hospital where two 15-year-old boys had self-transported with gunshot wounds, according to a Monday news release.

Investigators learned that three 15-year-old boys were inside a mobile home within the 1600 block of Sable Boulevard. There, one of the boys was playing with a gun before it discharged and struck himself and another boy, who later died in the hospital, according to police. The alleged shooter’s injuries were described as minor by police.

The third teenager, who was uninjured, drove the two wounded boys to the hospital, police said.

It remains unclear what the relationship is between the three boys, as police have withheld identities of those involved due to them being juveniles.

Officers later arrested the alleged shooter on second-degree murder charges. The Adams District Attorney’s Office will determine formal charges.

Investigators are working to learn where the firearm came from and why the boys were using it, according to police.

The investigation remains ongoing. Anyone with any information is asked to contact Metro Denver Crime Stoppers at 720-913-7867. Tipsters can remain anonymous and could be eligible for a reward of up to $2,000.