A Dallas police officer who allegedly entered an apartment that she believed was her own and fatally shot the resident was arrested Sunday for investigation of manslaughter.

Amber Guyger, 30, a four-year veteran with the Dallas Police Department, allegedly went into the wrong apartment in her building last Thursday night and fatally shot Botham Shem Jean, a 26-year-old native of the Caribbean island of St. Lucia.

Guyger, of Dallas, was arrested in Kaufman County and booked into the Kaufman County Jail, the Texas Rangers said in a statement.

Guyger was released Sunday night on $300,000 bail, NBC Dallas-Fort Worth reported.

The shooting just before 10 p.m. local time (11 p.m. ET) at the South Side Flats, an upscale apartment building south of Dallas’ downtown, occurred when Guyger was off-duty, police said.

Police said in a statement Friday that the officer “returned to what she believed to be her apartment after her shift ended,” and that “she was still in uniform when she encountered Mr. Botham Shem Jean inside the apartment.”

Police said it wasn’t clear what interaction occurred between the officer and the victim, but at one point the officer fired her weapon and struck Jean. The officer then called 911, and firefighters transported Jean to a hospital where he died.

Jean attended Harding University, a private Christian institution in Arkansas, and he belonged to the Good News Singers and the campus ministry. He worked for PricewaterhouseCoopers as an associate in its risk assurance department, the company said.

During a Friday night vigil, a friend of Jean's, Simba Musarurwa, described him as a kind, charismatic extrovert.

"He was a very uplifting kind of person," Musarurwa recalled. " He was probably one of the most likeable people I had ever met."

Jean's mother, Allie Jean, who lives in St. Lucia, said that Jean — her "heart" — had been taken by the officer.

"She took away my soul, she took away everything," she said Friday. "He didn't deserve to die like that."

A lawyer for the family, Lee Merritt, said Sunday that Guyger's arrest "was a step in the right direction," though he added that "most citizens would have been charged" on the night the crime occurred.

Allie Jean was "somewhat relieved" by the arrest, Merritt said. "However, she still has a lot of questions that she was disappointed couldn't be answered by the D.A."

It wasn't immediately clear if Guyger had a lawyer.

Guyger also shot someone on May 12, 2017, during what police described as "physical confrontation" in which a man allegedly grabbed an officer's stun gun, Dallas police said at the time.

In February, the man reached a plea agreement on a charge of taking an officer’s weapon and was sentenced to two years in prison, the Dallas Morning news reported.