Story highlights A video shows witnesses reacting to the Michael Brown shooting

They describe the teen holding his hands in the air

Their accounts coincide with several other witness descriptions of the shooting

CNN senior legal analyst says the new video is "good evidence"

Two men, shocked at what they saw, describe an unarmed teenager with his hands up in the air as he's gunned down by a police officer.

They were contractors doing construction work in Ferguson, Missouri, on the day Michael Brown was killed.

And the men, who asked not to be identified after CNN contacted them, said they were about 50 feet away from Officer Darren Wilson when he opened fire.

An exclusive video captures their reactions during the moments just after the shooting.

"He had his f**n hands up," one of the men says in the video.

The man told CNN he heard one gunshot, then another shot about 30 seconds later.

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Photos: Photos: Ferguson council meeting Photos: Photos: Ferguson council meeting Ferguson council meeting – Mayor James Knowles, seated right, and council members wait for angry residents to calm down during a City Council meeting in Ferguson, Missouri, on Tuesday, September 9. The meeting was held at Greater Grace Church to accommodate the large crowd. Residents used the meeting to express their anger at how the police and council handled the August 9 shooting of teenager Michael Brown and the unrest that followed. Hide Caption 1 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – Attendees shout during the meeting. The meeting was the first for the City Council since the fatal shooting of Michael Brown by a city police officer. Hide Caption 2 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – A man speaks loudly at the end of the meeting. Hide Caption 3 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – Marurice Brown raises his arms during the public comments portion of the meeting. Hide Caption 4 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – Louis Wilson addresses the City Council. Hide Caption 5 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – Angela Whitman listens along with the large audience. Hide Caption 6 of 7 Photos: Photos: Ferguson council meeting Ferguson council meeting – Patricia Cowan holds out her arms for a St. Louis County police officer as she and others are searched as they enter Greater Grace Church before the start of the meeting. Hide Caption 7 of 7

"The cop didn't say get on the ground. He just kept shooting," the man said.

That same witness described the gruesome scene, saying he saw Brown's "brains come out of his head," again stating, "his hands were up."

The video shows the man raising his arms in the air -- just as, he says, Brown was doing when he was shot.

The other contractor told CNN he saw Brown running away from a police car.

Brown "put his hands up," the construction worker said, and "the officer was chasing him."

The contractor says he saw Wilson fire a shot at Brown while his back was turned.

The men said they didn't see how the confrontation started.

Other witnesses also said teen's arms were raised

An attorney for the man who filmed the video says it was recorded 40 seconds after the shooting.

The construction workers said they don't live in Ferguson and don't know the Brown family, but their account squares with accounts from several other witnesses of the unarmed African-American teen's shooting death on August 9.

A private autopsy conducted for the Brown family showed that Brown had been shot at least six times, including twice in the head.

A grand jury is hearing the case and will determine whether Wilson will face any charges.

Protesters were near Interstate 70 and outside the police headquarters Wednesday, pushing for Gov. Jay Nixon to appoint a special prosecutor to investigate Brown's death.

Analysts debate video's impact

CNN senior legal analyst Jeffrey Toobin says the video could play an important role in the case.

"You have practically in real time someone discussing what they saw, and that's just good evidence," he said on CNN's "AC360."

Sunny Hostin, a CNN legal analyst and former federal prosecutor, says it's important to note that several witnesses are telling the same story.

"They're saying that he was running from the police officer and that his hands were up," she said. "I don't know what other witness testimony at this point or account we have to hear. The bottom line is having your hands up is the universal sign for surrender."

Neil Bruntrager, general counsel for the St. Louis Police Officers Association, cautioned against rushing to judgment. Witness accounts are important, he said, but need to be evaluated with all the evidence.

"I'm not saying disregard them. I'm saying that we will judge their credibility by all of the evidence, not by one statement, and certainly not by a 15-second video clip," he said.