A Portland police officer was fired and three others were suspended in connection with the fatal shooting of an unarmed black man by a white police officer, officials said Tuesday.

The discipline follows nearly 10 months of protests and tension between police and black leaders over the death of Aaron Campbell, 25, who was shot in the back Jan. 29 as he ran away from police.

The Rev. Jesse Jackson has called Campbell's death an "execution."

All four officers signed disciplinary letters on Monday and Tuesday. Officer Ryan Lewton was reprimanded for using a bean-bag gun without indications of violent behavior from Campbell, who emerged from his apartment walking backward with his hands on his head.

Officer Ron Frashour, a sniper who fired the lethal shot, was terminated for not complying with department policies on the use of deadly force. He has said he thought Campbell was reaching for a weapon, but police investigators determined that he was not reasonable in reaching that conclusion.

Sgts. Liani Reyna and John Birkinbine were reprimanded for communications failures. Both of them, along with Lewton, were suspended for two weeks without pay for unsatisfactory performance.

A Multnomah County grand jury found no criminal wrongdoing in the shooting, but said police training, command and communication were inadequate. Campbell's family has filed a federal lawsuit against the city and the four officers.

"This was a difficult decision because ultimately, I believe each Bureau member involved was attempting to do their best to resolve a complex situation," police chief Michael Reese said Tuesday. "However, as chief, I must address the significant issues that were brought forth."

Portland Mayor Sam Adams said "the discipline we have handed down is warranted."

The police union representing more than 900 Portland officers condemned the punishments, saying the officers did nothing wrong and were being used as scapegoats to minimize political fallout.

Portland Police Association President Daryl Turner said the officers will meet soon with union leaders and a lawyer to decide whether to file appeal the discipline to an independent arbiter.

"Today we can say that the rank-and-file of the Portland Police Bureau have lost faith in their leaders," the organization wrote on its website. "Disciplinary decisions cannot and should not be made for reasons of political expediency."

The Campbell incident began when police responded to a call for a welfare check at a Portland apartment complex. Campbell was distraught over his brother's death, had been drinking and had threatened suicide to his girlfriend, even taking out a .22-caliber pistol and pointing it at his head.

The girlfriend and her three children, including two of Campbell's, were removed from the scene and a police officer was negotiating with Campbell, hoping to end the standoff without incident.

Campbell emerged from the apartment with his hands on his head as Reyna, the police supervisor in command, was briefing her superiors around the corner of the building. One officer reacted by firing beanbags, another released a police dog and a third — Frashour — fired the fatal shot.

Campbell was unarmed, but police left him lying on the ground for more than 30 minutes before a special weapons unit arrived to confirm there was no weapon.

The state medical examiner's office said it was unlikely Campbell would have survived even if he had gotten immediate attention.

The Rev. Allen Bethel, president of the Albina Ministerial Alliance, which has criticized police conduct in the incident, welcomed Frashour's firing but said he'd like to have seen tougher suspensions for the other three officers.

"It does show that the bureau is beginning to take a look at these things that are being done and willing to hold the officers in the bureau responsible for the actions that have gone forth," Bethel said.