Largo, Florida - A 15-year-old Florida boy is accused of shooting his younger brother, who had himself fatally shot their 23-year-old sister as she sat outside with her baby on Christmas Eve, authorities said Tuesday.

Police said Damarcus and Darcus Coley had earlier gotten into a fight during a family shopping trip over who was getting what for Christmas.

When the siblings' mother took them all to their grandmother's house in Largo afterward, the fighting continued. The 14-year-old Damarcus reportedly pointed a semiautomatic handgun at his older brother's head and threatened to kill him.

The boys were separated by an uncle who managed to get Damarcus out of the home where his sister, Abrielle Baldwin, was sitting outside with her child. Baldwin is said to have asked her brother to end the dispute.

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This apparently only made him angrier. Damarcus reportedly berated and threatened to shoot her and her baby before firing a bullet into the woman's arm and chest. The baby was uninjured.

Darcus then emerged from the house with a semiautomatic handgun and shot his younger brother in the stomach. He then fled the home, throwing the gun into a nearby yard, and was later taken into custody at a family member's house.

Damarcus, who might be charged as an adult for first-degree murder, is in stable condition in a Tampa-area hospital after undergoing surgery. Darcus, meanwhile, has been charged with attempted first-degree murder and tampering with physical evidence.

The Pinellas County Sheriff's Department told the Daily News that "the investigation is still open and active, therefore the report is unable to be released at this time."