MEMPHIS — One person was fatally shot and a police officer was critically injured on Thursday afternoon in what the authorities described on social media as a “police-involved shooting” at a library in Memphis.

The Memphis Police Department, which has been under intense scrutiny after the beating that led to the death of Tyre Nichols last month, said that the person who was shot had been pronounced dead at the scene. The officer was taken to a hospital.

The Tennessee Bureau of Investigation, a state agency that scrutinizes police shootings, said on Twitter that the local district attorney, Steven J. Mulroy, had asked its agents to investigate the shooting.

The agency, which is also investigating Mr. Nichols’s death, said it would provide updates at the scene.

Mr. Mulroy’s office is leading the prosecution of five Memphis police officers who have been charged with second-degree murder in Mr. Nichols’s death after a videotaped beating in which officers punched and kicked Mr. Nichols and struck him with a baton.

This is a breaking news story. Check back for updates.