Columbia police were called to a residence twice Saturday regarding a man with a gun.
The second time, the suspect was fatally shot by officers.
Police say they were contacted Saturday afternoon by a woman who reported her son had a gun and was behaving oddly.
She said he had left the home in the 5800 block of Conveyor Street after they had a dispute.
Police arrived and located a machine pistol.
Saturday night, the woman called again to say that her son, 21-year-old Ajani Mitchell, had returned home with another gun.
Officers responded, found Mitchell behind the home and repeatedly ordered him to drop the weapon.
Police spokeswoman Jennifer Timmons says Mitchell did not comply and officers shot him.
He died at the scene.
The State Law Enforcement Division is investigating.