Crime Texas Teen Fatally Shoots Sister and Her Friend, Both 17, Before Turning Gun on Himself Investigators said 15-year-old Hayden Burns killed his older sister Hayley and her friend Kadience Cadena before ending his own life By Stephanie Wenger Stephanie Wenger Stephanie Wenger is a TV Writer/Reporter at PEOPLE. She joined the brand in 2021 as a digital news writer, covering stories spanning across the site's verticals. She previously contributed E! Online, Hollywood Life and Oscar.com. People Editorial Guidelines Published on January 21, 2022 04:14PM EST Photo: Brett Coomer/Houston Chronicle/AP Texas authorities have identified the three teens found dead inside a Crosby, Texas, home on Tuesday. On Thursday, the Harris County Sheriff's Department said that Hayden Burns, 15, shot and killed his sister, Hayley Burns, 17, and her friend Kadience Candena, also 17, before turning the gun on himself. The homeowner was out of town during the deadly incident. Harris County senior deputy Thomas M. Gilliland told PEOPLE the investigation is "still open and ongoing, our investigators are still trying to determine the motive of this tragic incident." 3 Texas Teens Found Dead with 'Signs of Trauma' in Apparent Double Murder-Suicide Dr. Anka Vujanovic, director of the University of Houston's Trauma and Stress Studies Center, told KHOU11 that this type of tragedy is unimaginable but there are often warning signs. "Murder-suicide, I think, is one of the most unfathomable acts of violence in our society," she said. She added, "Really listen when people talk about suicide, talk about dying from suicide or about hurting themselves or anyone else in any way." Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases. A next-door neighbor discovered Hayley's body in a hallway with a gunshot wound to the head, and Cadena's body was found with multiple gunshot wounds in a bedroom. Hayden's body was in another bedroom, the authorities said, according to the Houston CBS affiliate. Evidence found at the scene also shows that one firearm was used in all three deaths. "It's really surprising to see something like this happen out here to one of us," neighbor David Givans told KHOU11. "It's a close community for the most part. We all watch out for each other." The Crosby Independent School District also said in a statement, obtained by KHOU11, that they are "thinking of and praying for those who know" the victims, who were not current students. "Our hearts continue to go out to the families impacted by the tragedy in the Crosby community this week," the statement said. "District counselors have been made available at all campuses this week to speak with students and staff in need of extra support." If you or someone you know is considering suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255), text "STRENGTH" to the Crisis Text Line at 741-741 or go to suicidepreventionlifeline.org.