Updated at 9:45 p.m. with additional information.
Arlington police have made an arrest in the fatal shooting of a 39-year-old woman on New Year's Day.
Mario Alanis, 34, has been arrested in connection to the shooting death of his girlfriend Blanca Guerra, police said.
Alanis was taken into custody Friday evening in south Arlington. He was booked into the Arlington jail on a manslaughter charge.
Detectives allege he tried to shoot a firearm into the air as an act of celebratory gunfire for New Year’s when the gun did not initially go off.
Police claim Alanis then threw the loaded gun onto the ground and tried to reload it while it was pointed at Guerra. During this time, the firearm went off and hit her.
Officers responded around 12:25 a.m. to the scene on the 1600 block of Connally Terrace.
When they arrived, officers found Guerra on the back porch with a gunshot wound, police said. She was pronounced dead at the scene.
"A sister of the victim had called 911 to say 'Hey, I just received a phone call from my sister’s boyfriend, who said they went in the backyard, they were going to shoot a gun off to celebrate, and the gun accidentally went off and struck my sister,'" Lt. Christopher Cook told WFAA.
Alanis had left the scene by the time officers got there, Cook said.
"Sounds like they were, again, going to try and celebrate New Year's somehow with the firearm, and something terrible went wrong," Cook explained.
WFAA Digital Producer Jennifer Prohov and WFAA Digital Reporter Jay Wallis contributed to this report.