(CNN) Seattle Seahawks defensive end Michael Bennett, who is among prominent NFL players who protest the national anthem before games, said police in Las Vegas unfairly singled him out, threatened him with a gun and detained him briefly after he attended last month's prizefight between Floyd Mayweather Jr. and Conor McGregor.

As he was leaving a party at the casino and heading home, he said he heard what sounded like gunshots. While he and others ran for cover, Las Vegas police officers pointed guns at him "for doing nothing more than simply being a black man in the wrong place at the wrong time," he wrote.

One pointed a gun at his head while another pinned him to the ground before they handcuffed him and placed him in a squad car, he said. They released him upon learning who he was, but left him feeling as though "the system had failed me," he wrote on Twitter.

The Las Vegas Police Department confirmed that officers detained Bennett for 10 minutes and released him. They were responding to a call of battery and assault with a gun that had turned into an active shooter situation, Undersheriff Kevin McMahill said Wednesday.

Based on the information they had at the time, they believed Bennett may have been involved in the shooting and pursued him, McMahill said. Given the circumstances, McMahill said he saw "no evidence that race played a role in this incident."

'Emotionally traumatic event,' lawyer says

Bennett has hired civil rights attorney John Burris, who on Wednesday called the officers' actions "outrageous, and exhibit A as to how every black man rich, famous or poor, unarmed and innocent can be falsely detained, arrested or even shot and killed by the police," according to a statement.

Bennett, a father of three, feared for his life when he was detained, Burris told CNN.

"He was jumped, if you will, by these officers and told to get on the ground and, certainly, at gunpoint, it was uncalled for, it was an emotionally traumatic event," the attorney said. "You are placed in a position where your life can be in danger. If you make any sudden moves that could be misinterpreted by the police officers, you can lose your life."

In his account, Bennett said that as he lay on the ground, complying with his commands not to move, the officer placed his gun near his head and warned him that if he moved he would "blow my (expletive) head off."

While he was "terrified and confused by what was taking place," a second officer came over and "forcefully jammed his knee into my back making it difficult for me to breathe," he wrote. "They then cinched the handcuffs on my wrists so tight that my fingers went numb," he continued.

"The officers' excessive use of force was unbearable," Bennett continued. "I felt helpless as I lay there on the ground handcuffed facing the real-life threat of being killed. All I could think of was 'I'm going to die for no other reason than I am black and my skin color is somehow a threat.'"

McMahill said the officers were responding to the situation based on what they knew at the time. An individual later identified as Bennett was seen crouched down behind a gaming machine as the officers approached, he said. Once Bennett was in the officers' view, he quickly ran out of the south doors and jumped over a wall into traffic.

"Due to Bennett's actions and and the information officers had at the time, they believed Bennett may have been involved in the shooting and they gave chase," he said. "Many folks today have called this an incident of racial bias policing, that police officers focused solely on the race of the individual that they were going to stop. I can tell you as I stand here today, I see no evidence of that. I see no evidence that race played a role in this incident."

Bennett is considering filing a federal civil rights lawsuit for "unlawful detention," for the use of a firearm against him, and for being aggressively kneed in the back and handcuffed roughly, Burris said.

"Money cannot be the sole object for him because he makes a lot. I think he wants acknowledgment of what was wrong with what took place, and it's important from his point of view that when something like this happens, you stand up for yourself, you don't take the easy way out," Burris said.

Bennett expressed a similar perspective in his open letter: "Equality doesn't live in this country and no matter how much money you make, what job title you have, or how much you give, when you are seen as a 'Nigger,' you will be treated that way."

'The call that night was a scary one'

"The call that night was a scary one," Martellus Bennett wrote. "The emotion and the thought of almost losing you because of the way you look left me in one of the saddest places ever. I could hear the fear in your voice, the tears in your eyes as well your sprinting heart beat. I can't imagine how the people who lost their loved ones felt when they got the call."

Martellus Bennett added later: "To me, you're much more than a nigger," a direct reference to the line in his brother's open letter.

Also responding to Bennett's letter Wednesday was Colin Kaepernick, the ex-San Francisco 49ers quarterback who became a lightning rod last year when he refused to stand during the national anthem to protest what he believes are racial injustices and ongoing police brutality in the US.

"This violation that happened against my Brother Michael Bennett is disgusting and unjust. I stand with Michael and I stand with the people," Kaepernick tweeted

In an interview last month with CNN , Bennett said he won't stand for the national anthem at NFL games until he sees "equality and freedom."

"At this point, I think if you're being silent, you're being dishonest," Bennett told CNN. "And we can be silenced no more because we're living in this reality where I can't hide behind the logo on my helmet. I can't hide behind the shield. I can't hide behind the glamor and glitz of the NFL."

Kaepernick, who last year said he didn't want to "show pride in a flag for a country that oppresses black people and people of color," drew fierce criticism for refusing to stand during the national anthem but also inspired athletes -- from elementary schools to professional leagues -- to join his movement.

Kaepernick remains a free agent, as no NFL team has signed him.