“The individuals involved in his murder took away a man with children who depended upon their daddy on a daily basis,” Ms. McMillon said, adding, “As a mother I have now been forced to raise a son who is going to remember what happened to his father.”

On Tuesday, a person called the police to report that a black man in a red shirt selling music CDs outside the Triple S Food Mart had threatened him with a gun, the Police Department said. Two officers confronted Mr. Sterling about 12:35 a.m.

Mr. Sterling had a long criminal history, including convictions for battery and illegal possession of a gun, but it is not clear whether the officers knew any of that as they tried to arrest him.

The graphic cellphone video shot by a bystander, which was released later in the day, shows an officer pushing Mr. Sterling onto the hood of the car and then tackling him to the ground. He is held to the pavement by two officers, and one appears to hold a gun above Mr. Sterling’s chest.

At one point someone on the video can be heard saying, “He’s got a gun! Gun!” and one officer can be seen pulling his weapon. After some shouting, what sound like gunshots can be heard and the camera shifts away, and then there are more apparent gunshots.

A second video of the shooting, filmed by the owner of the store and first posted by the local newspaper, The Advocate, on Wednesday afternoon, showed the shooting from a different angle. It also shows one of the officers taking something out of Mr. Sterling’s pocket after he was shot and was lying on the ground.