A police officer in Arizona has been fired after shooting a 61-year-old disabled man nine times in the back on Monday night.

Tucson police officials said at a news conference on Tuesday that Ryan Remington was terminated for excessive use of force in the death of Richard Lee Richards, who was in a motorized wheelchair when the officer repeatedly shot him in front of a home improvement store.

The shooting at the Midvale Park Shopping Center was recorded on security cameras and police body cameras, and the videos were subsequently shared on social media. Body camera footage shows Remington and Officer Stephanie Taylor confronting Richards from a few feet behind as he steers his wheelchair toward a Lowe’s entrance.

“Do not go into the store, sir,” an officer is heard telling Richards, who appears to ignore the warning. Taylor is then heard saying, “Stop now, you need to … ” before Remington begins shooting at Richards in the back and side at close range, based on what’s shown on the video. Lowe’s security footage shows that a store employee was also near the Lowe’s entrance, ahead of Richards, and could have been struck by one of Remington’s bullets.

In the graphic footage, Richards then slumps over and falls out of his chair. Remington is then seen rushing toward him, and he handcuffs the man as he’s crumpled on the ground instead of trying to administer lifesaving aid. Richards was pronounced dead soon afterward.

Remington’s actions were “unconscionable and indefensible,” Tucson Mayor Regina Romero said in a statement to local media.

“It is moments like this that test our resolve to ensure justice and accountability,” she said. “We owe this to all Tucsonans. I ask our community to remain calm and be patient as investigations ensue.”

Tucson Police Chief Chris Magnus said Tuesday that a Walmart employee reported that Richards was suspected of shoplifting a toolbox, and when he was asked to show a receipt, Richards reportedly pulled out a knife and said, “Here’s your receipt.” Richards then began to head toward the Lowe’s store across the parking lot, according to police.

Remington, who Magnus said served as a security liaison for the store, was alerted to the confrontation and followed Richards in the parking lot. Video shows the officer calling for backup because Richards “pulled a knife on me.” Taylor responded and arrived at the scene as Remington began approaching Richards near the Lowe’s, but before she could finish telling Richards to stop, Remington began firing at him.

“To be very clear, I am deeply disturbed and troubled by Officer Remington’s actions,” Magnus said. “His use of deadly force in this incident is a clear violation of department policy and directly contradicts multiple aspects of our use-of-force training.”

Remington’s attorney Mike Storie, who represents officers in the police union, told The Arizona Republic that his client “had no non-lethal options” despite Remington having a Taser and the ability to turn off Richards’ wheelchair.

“He did have a Taser, but in his mind, he couldn’t use it because he didn’t feel he had the proper spread to deploy it, with the wheelchair between him Richards,” Storie told the Republic, not including the fact that the wheelchair between Remington and Richards did not stop the officer from shooting the man nine times.

The mayor tweeted on Tuesday that the police union “is not the most objective arbiter in this matter,” and that “the video speaks for itself.” The Pima County Attorney’s Office is currently reviewing the shooting for potential criminal charges against Remington.

A lawyer who had represented Richards in a criminal case told The New York Times that Richards used a wheelchair due to a hip replacement and other physical issues.

Richards’ death came one day after Tucson police announced they were investigating an incident in which an off-duty officer pinned a mother and daughter to the ground at a restaurant last month. Police announced their investigation following an Arizona Daily Star columnist’s lengthy account of the incident, along with video.

“Understandable anger & frustration concerning two recent incidents involving our dept. I appreciate those concerns. We’re working to be as responsive & transparent as possible,” Magnus tweeted Tuesday. “Thanks for feedback but I’ll block obscenity and incivility since it adds nothing to the conversation.”