A Dallas police officer arrived in full uniform on Thursday night at an apartment she thought was hers, entered it, and shot and killed a man who lived there, police said, citing the officer's account of what happened.

Once inside the wrong apartment, the officer fired her weapon, striking the victim, a 26-year-old male, who was treated at the scene by responding officers and pronounced dead later after being taken to hospital, the Dallas Police Department said in a statement on Friday. 

The officer lived in an apartment on another floor of the same apartment complex

The 26-year-old officer told investigators she thought she had entered her own residence, the statement said.

The officer, who was not injured, was placed on administrative leave, pending the outcome of a joint investigation by Dallas police and the local district attorney, the statement said.

The Dallas County Medical Examiners Office said the man killed was Botham Shem Jean, and that an autopsy was being performed on Friday morning.

The St Lucia Times, a newspaper published on the Caribbean island of Saint Lucia, said Jean was the son of a former permanent secretary of that island nation.

Dallas police, reached by phone on Friday, would not confirm the man's identity.

The newspaper said the dead man had been an employee of PricewaterhouseCoopers and lived in a gated community.

Citing a relative of Jean, the St Lucia Times reported that the officer lived in an apartment on another floor of the same apartment complex.