A Colorado teen allegedly gunned down a 15-year-old girl after she broke up with him in a terrifying confrontation at her home, all of it in front of the victim’s younger brother, KUSA-TV reports.

Details about the June 16 tragedy in Greeley, a Denver suburb, were made public this week. Authorities allege that 16-year-old Jovanni Sirio-Cardona broke into the home of his former girlfriend, Lily Silva-Lopez, through her bedroom window.

Silva-Lopez screamed and told her 13-year-old brother to flee just seconds before Sirio-Cardona allegedly fired multiple bullets into the girl.

Sounds of the gunfire terrified neighbors, some of whom hid in their homes, according to KMGH-TV.

The younger brother told police his sister’s body was on the floor of a hallway and that Sirio-Cardona stood over her holding a gun with blood running from his nose.

The brother begged for his life and Sirio-Cardona allegedly took his phone so he could not call police. Sirio-Cardona then forced the brother to help move his sister’s body but ended up dragging the girl back to her bedroom by himself.

After Sirio-Cardona fled the scene, the brother escaped to a neighbor, who called 911.

Silva-Lopez and Sirio-Cardona had dated for six months but she sought to end the relationship several weeks before the slaying. In response to the girl trying to break up, Sirio-Cardona allegedly stuck the barrel of a gun into her mouth and told her that “she wasn’t going to break up with him and she needed to tell him she loved him,” KUSA-TV reports, citing an affidavit filed in court.

Just six days before the killing, the girl reported that Sirio-Cardona had punched her face and injured her arms. He had also allegedly stalked her home days before the murder.

Silva-Lopez was set to turn 16 on June 21 and had just finished her sophomore year of high school.

“She enjoyed shopping, clothes, makeup and dancing. She loved to eat! Enchiladas were her favorite. She loved animals. She was a loving and caring friend with lots of spice,” her family wrote in her obituary.

Prosecutors in Weld County have charged Sirio-Cardona as an adult instead of routing him through the state’s juvenile justice system; he faces charges of first-degree murder, second-degree murder, burglary, aggravated robbery and possession of a handgun by a juvenile.

When police went to Sirio-Cardona’s home following the shooting, his grandmother asked why officers were there. He allegedly responded that “he did what he had to do and shot someone,” according to KUSA-TV, citing court documents.

For help dealing with domestic violence, call the National Domestic Violence Hotline at 1-800-799-7233.

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[Feature Photo: Lily Silva-Lopez/Adamson Life Celebration Home]