Authorities said that deputies responded to the shooting in the 200 block of W. Canino Road after receiving the call at about 10:50 a.m. on Sunday.
Investigators said the suspected gunman, 19-year-old Angel Javier Rodriguez, is the teen's ex-boyfriend and the father of her young child. They added that he was arrested shortly after the shooting without incident on Will Clayton Parkway, about 20 minutes from the crime scene.
Deputies said that when they responded to the home, they found the siblings suffering from multiple gunshot wounds. Both were pronounced dead at the scene.
According to investigators, the teen was outside when her ex-boyfriend arrived to confront her. Authorities said her older brother came outside and attempted to shield his sister before the suspect opened fire, striking and killing both siblings.
Investigators said the victims were each shot multiple times. They also believe the suspect fired at several other people at the scene, but no one else was struck.
The victims' mother was also targeted during the shooting, authorities said, but she was not injured.
"We understand the mother was shot at as well," Sgt. Michael Ritchie said. "She just lost a son and a daughter."
Authorities said Rodriguez surrendered peacefully when deputies located him.
In an update on Sunday night, Sheriff Ed Gonzalez shared that Rodriguez was charged with capital murder and was booked into the Harris County Jail. If convicted, a capital murder conviction carries a sentence of life in prison without the possibility of parole, or the death penalty if prosecutors pursue it and the legal requirements are met.
The sheriff's office said the couple shared a young daughter and that investigators were still working to determine the circumstances surrounding the end of their relationship.
"Unfortunately for that child, today that child just lost both their parents," Ritchie said. "One's deceased and one's going to be in prison the rest of their life."
Neighbors said they remembered seeing the teen caring for her daughter and described the shooting as heartbreaking.
"It's sad. So sad. Really sad," neighbor Claudia Hernandez said.
The investigation remains ongoing.