Four Houston police officers were fired Thursday after a months-long investigation of a fatal shooting found that they were "objectively unreasonable" in discharging 21 rounds at a man in distress.

On April 21 at around 9 p.m., multiple officers responded to several 911 calls about a man who was running through highway traffic.

Officers approached Nicolas Chavez, 27, in a parking lot, where he was running while holding a metal object, police said. During a roughly 15-minute interaction, officers shot Chavez with stun guns and bean bags while attempting to "stop him from harming himself," Houston Police Chief Art Acevedo said in a video compilation of the body-camera footage that was also released Thursday.

Throughout the incident, five officers fired 24 rounds at Chavez, Acevedo said at an at-times emotional press briefing Thursday. Three of those shots were found to be "objectionably reasonable," while the final barrage of 21 shots by four officers was not, he said, because Chavez "was at his greatest level of incapacitation."

Acevedo detailed that before the 21 shots in question, police officers had shot Chavez more than once, discharged five cartridges of stun guns and deployed six bean bags.

"I believe that anyone that watches this tape, and sees this, will see they had a lot of opportunities and a lot of other options readily available to them that we, as long as I'm the police chief of this city, I will expect my officers to take," Acevedo said.

The four officers fired were Sgt. Benjamin LeBlanc, who discharged two of the 21 shots; Omar Tapia, who discharged six; Patrick Rubio, who discharged six, and Luis Alvarado, who discharged seven.

LeBlanc, a 12-year veteran of HPD, also fired the first two shots, and a fifth officer, Kevin Nguyen, fired one, for 24 total rounds. All five officers were placed on administrative leave following the shooting.

Houston Mayor Sylvester Turner said at Thursday's press briefing that the incident "has dramatically affected many people in this city."

"This video is difficult to watch, and I have seen it several times," he said. "It's difficult to watch without questioning why the shooting happened in the end, and wishing the encounter could have ended differently and knowing that it should have had a different outcome."

He said that "for almost the entire time," he found no fault in the police officers' actions, but agreed that the final shooting was "not justified in this case."

"Mr. Chavez posed a threat to himself," he said. "And he too could have lived and could have gotten the help that he desperately needed."

Getting choked up, Turner stressed that the decision to dismiss the officers "is not an indictment on HPD."

Joe Gamaldi, the president of the Houston Police Officers' Union, responded that the four officers were "fired today for a justified shooting," and called the decision "unjust and deplorable."

"[Even] if you deescalate, retreat, follow policy, training and the law... you will still lose your job as a Houston Police Officer," he said on Twitter.

Acevedo had promised in April that the department would look into the incident following the release of cellphone footage that captured the barrage of 21 shots fired.

The department's Special Investigations Unit and Internal Affairs Division reviewed nearly 25 hours of footage from 39 videos, Acevedo said. In the nearly 17-minute compilation of several officers' body-camera footage released Thursday, 911 calls reporting a man in distress walking through traffic on a highway and through residents' yards are included. Chavez was distraught and "apparently suicidal," the police chief said in the video.

While addressing Chavez in a parking lot, officers can be heard ordering him to get on the ground. After he doesn't comply, officers deploy bean bags and stun guns. Chavez appears to move toward one of the officers while holding a metal object, according to police. At that point, LeBlanc fires two shots, striking Chavez. Nguyen later fires a third.

While on the ground, Chavez, who is visibly bloodied, throws the object and starts pulling a stun gun by its wires toward himself. He grabs it, at which point the four officers fire 21 shots. The stun gun was ultimately empty, though the officers said they were not aware of that, according to the police chief.

"Let me be clear -- it's objectively not reasonable to utilize deadly force when a man's already been shot multiple times, has been tased, has been on the ground, has shown that he really cannot get up," Acevedo said Thursday. "I cannot defend that."

There were 28 officers on the scene, Acevedo noted.

Chavez was transported to a local hospital, where he died, authorities said. The medical examiner later determined that Chavez had 29 wounds from bullets, skip rounds (bullets that struck the ground first) and bullet fragments entering and exiting, according to Acevedo.

The autopsy revealed that Chavez had methamphetamine, amphetamine and ethanol in his system, according to Acevedo.

Harris County District Attorney Kim Ogg said in a statement Thursday that her office is reviewing the incident and plans to present a case directly to a grand jury that will "determine whether the Houston police officers who shot Nicolas Chavez were justified or whether they committed a crime."

"I met with the mother, father and wife of Nicolas Chavez to listen to their concerns and personally assure them that our Civil Rights Division prosecutors will conduct a thorough, independent review of all the evidence in his death," she said in the statement.

In a press conference Thursday, Chavez's mother, Leantha Chavez, said she was "elated" over the dismissal of the four officers, but called for them to be charged, according to the Houston Chronicle .

"It's very hard to be happy and sad about something so tragic," she said, the paper reported. (ABC News)

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