Colin Kaepernick's decision to protest the national anthem during each of the 49ers' three preseason games this year has left him in hot water with a police organization in California.

The San Francisco Police Officers Association sent out a letter on Monday blasting Kaepernick's actions.

"While we certainly acknowledge Mr. Kaepernick's first amendment right to remain seated during the National Anthem, as inappropriate as it may be, we will not stand by while he attacks police officers with statements such as 'People are on paid leave while people of color are killed,' " Halloran wrote.

Colin Kaepernick is in hot water with the San Francisco police union. USATSI

During an 18-minute interview on Sunday, Kaepernick said that one of the big reasons he was protesting the national anthem is because he has an issue with several things going on in across the country, including police brutality.

"There's a lot of things that need to change," Kaepernick said, via "One specifically? Police brutality. There's people being murdered unjustly and not being held accountable. People are being given paid leave for killing people. That's not right. That's not right by anyone's standards."

The 49ers quarterback also added that be believes cops are targeting minorities.

"There is police brutality," Kaepernick said. "People of color have been targeted by police. So that's a large part of it and they're government officials. They are put in place by the government. So that's something that this country has to change. There's things we can do to hold them more accountable. Make those standards higher."

In the two-page letter, Halloran called Kaepernick an embarrassment to both the 49ers and the NFL.

"I only wish Mr. Kaepernick could see the emotional and psychological challenges that our officers face following a fatal encounter," Halloran wrote. "Some are so affected they never return to the streets. In short, Mr. Kaepernick has embarrassed himself, the 49er organization, and the NFL based on a false narrative and misinformation that lacks any factual basis."

One of the facts that Kaepernick brought up during his interview on Sunday was the lack of training it takes to become a cop.

"You have people who practice law, lawyers, who go to school for eight years, but you can be a cop in six months," Kaepernick said. "You don't have to do the same amount of training as a cosmetologist. I mean someone with a curling iron has more education and training than people who have a gun. That's insane."

Halloran has invited Kaepernick to attend a police training session so that the 49ers quarterback can see what really goes into becoming a police officer.

"As a gesture to build communication and understanding about the law enforcement profession," Halloran wrote. "The SFPOA extends an open invitation to Mr. Kaepernick and to any player or employee from the the [NFL] to visit the SFPD academy and partake in any of the simulations that recruits partake in during their training."

Although the 49ers offered an initial statement on the Kaepernick situation following Friday's game against the Packers, the team has yet to respond to the letter from the police union.