Updated at 5:30 p.m. Saturday: Revised to include the name of the officer.

A Dallas officer faces a manslaughter charge after she fatally shot a 26-year-old man whose apartment near downtown she apparently mistook for her own.

"This is a very unique situation," Police Chief U. Renee Hall said at a news conference Friday afternoon. "We have ceased handling it under our normal officer-involved shooting protocol."

The Texas Rangers have been called in to conduct an independent investigation, the chief added.

Officer Amber Guyger has not been officially named in connection with the shooting, but a source within the Dallas Police Department has identified her. The chief said the officer's blood was drawn to test for alcohol and drugs.

The officer, a five-year veteran, wasn't hurt in the incident, which happened about 10 p.m. Thursday at the South Side Flats, at 1210 S. Lamar St. The location is just blocks from police headquarters in the Cedars.

Botham Jean, 26, was a graduate of Harding University in Arkansas, where he had been a beloved worship leader. (Facebook)

Police officials said she arrived at the complex after working a full shift and was still in full uniform when she entered the victim's apartment, thinking it was hers.

The victim was identified as Botham Shem Jean, a native of the Caribbean nation of Saint Lucia and an employee at PricewaterhouseCoopers in Dallas.

Jean was a graduate of Harding University in Arkansas, where he had been a beloved worship leader. University officials mourned during their chapel services Friday morning, a campus employee said. Spokeswoman Jana Rucker said that the university was "deeply grieved" and that Jean was "one of those people who really stood out, with his voice and his leadership."

The Dallas police chief said she had talked to Jean's family after the shooting and "reassured them that we are working diligently."

The victim's mother was visiting her daughter in Florida when she got a call delivering the news of her son's death.

"It just feels like a nightmare. I wish I could wake up," Allison Jean told NBC News. "He impacted the lives of many. I'm getting calls from all over the world."

The officer who shot Jean is white, and Jean said she wondered whether the outcome would have been different if her son hadn't been black.

"I don't want to judge her. We are Christians. We forgive," she said. "But I need to look into her eyes and ask her why did she do that to my son.

"She took away my heart. My soul. He didn't deserve to die."

Hall said police had "more questions than we have answers" about what transpired late Thursday.

As of late Friday, authorities had yet to fully explain how the situation escalated to the shooting, declining to comment on whether the officer mistook Jean for an intruder.

"I won't go into that information right now," said Sgt. Warren Mitchell, a police spokesman. "We have not interviewed her. ... We still have a lot to do in this investigation."

Officials said that after the officer reported that Jean was wounded, other police arrived within four minutes and administered first aid. Jean was taken to Baylor University Medical Center, where he was pronounced dead.

The officer was placed on leave while the shooting is investigated with the Dallas County district attorney's office.

It was unclear how the officer got into the wrong apartment, where residents said they can access their units with a regular key or a keypad code.

Next-door neighbor Alyssa Kinsey said Jean's unit looked the same as everyone else's from the outside but did have a red half-moon-shaped rug outside the front door.

Kinsey said she has parked on the wrong floor and gotten mixed up while returning to her unit in the South Side Flats. But, even when lost or coming home at night, she's never felt she had to be on alert in the hallways.

"It's like Fort Knox in here," Kinsey said. "It's so safe."

When Kinsey heard the gunshot at her neighbor's front door Thursday night, she assumed it was a domestic dispute.

"I didn't hear any knocking or yelling beforehand, just the shot," she said. "And then the woman's voice calling 911."

Police didn't indicate that anyone had witnessed the shooting, but two other women who live on the second floor near where the shooting happened said they heard a lot of noise late Thursday.

"It was, like, police talk: 'Open up! Open up!'" 20-year-old Caitlin Simpson said.

Yazmine Hernandez, 20, was studying with Simpson when they heard the commotion.

"We heard cops yelling," she said, "but otherwise had no idea what was going on."

Other residents of the South Side Flats struggled to understand how the shooting had happened.

"How can you make a mistake like that, getting into someone else's apartment?" said 80-year-old Raquel, who has lived in the complex for less than a year. "Don't they train police?"

The woman, who said she never gives out her last name, said she'd think twice when calling the police after this experience.

"Now if something happens to me," she said, "I'm going to be too scared to call police because I'm afraid it will end in a tragedy."

Tomiya Melvin lives in a nearby apartment complex and learned of the shooting while walking her dog in the morning.

"It's terrible. I hope it's just a tragic accident and nothing more than that," said Melvin, who moved to Dallas from Chicago in June. "This area appealed to me because it always seemed so safe, and so far it has been.

"But I won't be leaving my door unlocked anymore; that's for sure."