Update at 11:30 a.m. Wednesday: Revised to include the slain man's name.

A man fatally shot a person who he said threatened to kill him outside a cellphone store in Oak Lawn on Monday morning.

Dallas police were called to the AT&T store in the 3300 block of Oak Lawn Avenue, at Rawlins Street, when a shooting was reported just before 10 a.m.

The 911 caller said someone had run up and threatened to kill him, police spokeswoman Melinda Gutierrez told KXAS-TV (NBC5). The caller, who has a concealed-handgun license, pulled out a gun and shot the other person, she said.

Numerous police vehicles were at the scene Monday as authorities investigated, and one person was being detained in a cruiser.

The Dallas County medical examiner's office identified the slain man as Alexander Horton, 31.