Obdulia Sanchez aimed the camera phone at her face as she rapped along to the song blaring over the radio and tried to control the car she was driving on a road in California's Central Valley.
Then came tragedy, live-streamed in a horrifying Instagram video.
The California Highway Patrol told Fox affiliate KTXL that Sanchez, 18, lost control of her 2003 Buick, drove off the edge of the road and then overcorrected. The car crashed into a barbed-wire fence and flipped over in a field, according to ABC affiliate KFSN.
Sanchez's 14-year-old sister, Jacqueline, and another teen girl - who were in the back seat and were not wearing seat belts - were ejected from the tumbling car.
Moments later, Obdulia Sanchez was on Instagram Live again, explaining what happened - and growing increasingly hysterical.
"Hey, everybody, if I go to jail for life, you already know why," she began, adjusting the camera so it showed her younger sister, motionless and bleeding from the head.
"My sister is dying. Look, I love my sister to death. Man, we about to die. This is the last thing I wanted to happen to us, but it just did. Jacqueline, please wake up."
"I don't care though," Sanchez continued. "I'm a hold it down. I love you, rest in peace, sweetie. If you don't survive, baby, I am so sorry. I did not mean to kill you, sweetie. Sweetie, I am sorry. Sweetie, please, wake up!"
Authorities say 14-year-old Jacqueline Sanchez died at the scene.
Jacqueline was pronounced dead shortly afterward.
Obdulia Sanchez was in Merced County Jail on Monday, accused of driving under the influence of alcohol or drugs and gross vehicular manslaughter.
The other girl, whom authorities have not identified, had major trauma to her right leg but is expected to survive.
Obdulia Sanchez complained of pain in her chest and right knee after the crash.
Her sister was supposed to celebrate her quinceanera, or 15th birthday, on Sunday, according to a GoFundMe page set up to help cover the dead teen's funeral expenses.
California Highway Patrol Sergeant Darin Heredia told BuzzFeed News that officials were "well aware" of the video. They are trying to determine whether it's legitimate and, if so, whether Sanchez's phone use contributed to the crash.
