The Florida brother told authorities it was an accident.
A Florida teen has been arrested after his 13-year-old sister was found dead with a gunshot to the head this week.
Martaevious Santiago was celebrating his 17th birthday Tuesday before the death of his sister, Tedra King.
Read: Teen Accidentally Shoots, Kills Self on Instagram Live as Friends Watch
Santiago frantically called 911 to say he'd accidentally shot his sister in their Florida City home, cops told WSVN.
Police said Santiago was holding a loaded semi-automatic handgun when his sister gave him a hug. As she turned around to walk away, the boy allegedly pointed the handgun to the back of his sister's head and pulled the trigger.
King was pronounced dead at the scene. Santiago was placed under arrest and has since been charged with aggravated manslaughter.
Santiago's stepfather, Vernon Williams, became emotional as he described to reporters the moments that followed Tedra's untimely death.
"All he said [was], ‘Daddy, I’m sorry. It was an accident. I’m sorry, Dad.’ Those were the words," Williams said.
A judge ordered the teen held while it's decided whether he will be charged as an adult.
Another juvenile, this one a 14-year-old boy, has also been detained in connection with the case after cops say he provided the firearm to Santiago. That boy was taken into custody for an outstanding delinquency warrant.
Watch: Parents Disarm 15-Year-Old Son Who Stole Guns and Brought Them to School: Cops
