A Louisiana police officer shot and killed a man during a confrontation outside a Baton Rouge convenience store, authorities said, in a death that prompted a protest later in the day.

An autopsy shows Alton Sterling, 37, of Baton Rouge, died Tuesday of multiple gunshot wounds to the chest and back, East Baton Rouge Parish Coroner Dr. William Clark said.

Officers responded to the store about 12:35 a.m. Tuesday after an anonymous caller indicated a man selling music CDs and wearing a red shirt threatened him with a gun, Cpl. L'Jean McKneely said.

Two officers responded and had some type of altercation with the man and one officer fatally shot the suspect, McKneely said. Both officers have been placed on administrative leave, which is standard department policy, he said.

The store's owner, Abdul Muflahi, told WAFB-TV that the first officer used a stun gun on Sterling and the second officer tackled the man. Muflahi said as Sterling fought to get the officer off of him, the first officer shot him "four to six times."

The owner said Sterling did not have a gun in his hand at the time but he saw officers remove a gun from Sterling's pocket after the shooting.

McKneely said late Tuesday that he could not confirm Muflahi's description of the event or any other details of the investigation.

The Advocate reported a crowd of people protesting the shooting gathered late Tuesday afternoon at the store where it took place. The group grew to over 200 people, who chanted "black lives matter" and "hands up don't shoot" and waved signs late into the night, according to the newspaper.