(CNN) A video that shows an unarmed African-American man lying in the street with his arms in the air doesn't tell the whole story of what happened when North Miami police shot the man earlier this week, a union official told reporters.

An officer accidentally shot behavior therapist Charles Kinsey, according to John Rivera, president of the Dade County Police Benevolent Association. The officer, Rivera said, had been aiming for the patient beside Kinsey, whom he thought posed a danger.

A video released by Kinsey's attorney has sparked outrage. The video shows the scene before Monday's shooting: A white man sits cross-legged on the ground, holding an object in his hand. Kinsey, who is black, lies on the ground, holds his hands in the air and yells to police that the man beside him is holding a toy truck, not a weapon.

Rivera offered an explanation Thursday, saying that the police officer opened fire because he thought the white individual, whom authorities later learned has autism, was going to harm Kinsey.

"This wasn't a mistake in the sense that the officer shot the wrong guy or he thought that Kinsey was the bad guy," Rivera said in a press conference Thursday.

"The movement of the white individual made it look like he was going to discharge a firearm into Mr. Kinsey and the officer discharged trying to strike and stop the white man and unfortunately, he missed the white male and shot Mr. Kinsey by accident."

Rivera said that the video footage of the shooting was "being portrayed poorly."

Kinsey is hospitalized with a gunshot wound to his right leg after two or three shots were fired, according to his attorney.

"Mr. Kinsey did everything right, let's be real clear about that," Rivera said. He said that the police officer involved in the shooting "wishes nothing but the best for Mr. Kinsey and the officer is praying for his speedy recovery as are we."

Kinsey told CNN affiliate WSVN-TV in Miami that after the shooting, he was flipped over and handcuffed. A video released by his attorney showed Kinsey lying in the road, on his stomach and handcuffed. Both men were seen flat on the ground, with two officers standing near them.According to his attorney Hilton Napoleon II, Kinsey was on the ground for 20 minutes before an ambulance arrived.

Officer: 'I did what I had to do'

Authorities haven't released the name of the officer who opened fire. In a fact sheet released via social media, police said the officer involved in the shooting is a 30-year-old Hispanic male with four years on the job.

North Miami police have said officers responded to a 911 call about an armed man threatening to commit suicide, and opened fire after police attempted to negotiate. Kinsey and his attorney say that the police explanation doesn't add up. State authorities said they're investigating the shooting.

The unidentified officer, who has been placed on administrative leave, issued a statement in the form of a text message, which Rivera read to reporters.

"I took this job to save lives and help people," according to the officer's text statement. "I did what I had to do in a split-second to accomplish that, and hate to hear others paint me as something I'm not."

Kinsey told WSVN that his patient was holding a toy truck, not a gun. He said he tried to explain the situation to officers.

Kinsey said the footage showed the moment when he tried to persuade police not to harm his patient. He asked his patient to be still and lie down.

"Please be still ... get down ... lay on your stomach," Kinsey says in the video.

The man beside him rocks back and forth.

"I was more worried about him than myself," Kinsey told WSVN.

"As long as I've got my hands up, they're not gonna shoot me, that's what I'm thinking," he said. "Wow, was I wrong."

So far, Napoleon said, video of the shooting itself hasn't surfaced.

State takes over investigation

Reports of the North Miami shooting drew swift reactions on social media, with posts criticizing the officer who opened fire.

Kinsey's shooting comes after a pair of officer-involved shootings led to the deaths of two men,Alton Sterling and Philando Castile, kicking off a period of national unrest and putting the spotlight again on police use of force, particularly against black men. Kinsey also is black.

Protesters flooded the North Miami Police Department headquarters Thursday, demanding answers.

Eight law enforcement officers have since been killed in separate incidents in Dallas and Baton Rouge, Louisiana, targeted by gunmen who claimed they were reacting in part to shootings such as those that led to the deaths of Sterling and Castile.

The Florida Department of Law Enforcement is investigating KInsey's shooting.

"Bringing in an outside agency assures our commitment to transparency and objectivity in a very sensitive matter," North Miami police Chief Gary Eugene said.

Prosecutors said they'll decide whether the officer should be charged after the state agency completes its investigation.

"They will provide us with their factual findings and conclusions," Miami-Dade State Attorney Katherine Fernandez Rundle said. "At that time, we will conduct our own investigation and review all of the evidence to determine whether the actions of the shooting officer constitute a criminal act that can be proven beyond and to the exclusion of every reasonable doubt."

'This is not supposed to be happening in North Miami'

Howard Simon, executive director of the American Civil Liberties Union of Florida, condemned the shooting: "Thankfully, Mr. Kinsey is alive and not more gravely injured -- but had the officer's weapon been pointed just a few degrees differently, this senseless incident could have been a much greater tragedy."

Simon called on law enforcement agencies to examine policies on the use of force and responses to people with mental health issues.

"Without changes in policy and improved training of officers, we will very likely see more needless shootings and deaths at the hands of police," he said in a statement.

A U.S. congresswoman whose district includes North Miami told reporters she was shocked by the video that shows the scene before the shooting.

"This is like a nightmare to me," Democratic Rep. Frederica Wilson said.

"When you shoot a man lying on the ground with his hands up, explaining to you the situation, and you shoot him anyway? Something's not right with this picture," she said.

The shooting she said, isn't typical of the city, which she described as a "melting pot."

"This is not supposed to be happening in North Miami. North Miami is a city where the police officers and the community gel," she said. "So many of our police officers come from the community (and) live in the community."