Detective Charles "Chuck" Dinwiddie died at 2:14 p.m. from a gunshot wound to the head.
He and three other officers were shot at while serving a narcotics warrant at a residence on Circle M. Drive.
Two of the officers hit by bullets were protected by safety equipment and a third, Odis Denton, was shot in the femur and was recovering from surgery at Scott & White Memorial Hospital. He's listed in good condition.
"Our community has suffered a great loss. Few people have touched the number of lives, in such a meaningful way, as Detective Dinwiddie," Killeen Police Chief Dennis Baldwin said.
"As a dedicated professional, his service to the Killeen community was with honor, courage, and unwavering loyalty. Our hearts and prayers go out to his family and friends during this difficult time."
Marvin Louis Guy, 49, was arrested in the shooting and was charged with three counts of attempted capital murder. He was being held at Bell County Jail in lieu of $3 million bond.
A 50-year-old woman was also arrested, though her name and any charges she may face weren't reported.