Charles Rex Arbogast/Associated Press

Paul Smith, the volunteer fire chief at Muse Fire Department in Cecil Township, Pennsylvania, apologized Monday for using a racial slur in reference to Pittsburgh Steelers head coach Mike Tomlin.

According to Pittsburgh's Action News 4, Smith said, "Tomlin just added himself to the list of no good n-----s. Yes I said it," in a Facebook post.

Smith later apologized, saying, "I am embarrassed at this. I want to apologize. I was frustrated and angry at the Steelers not standing for the Anthem. My FD had absolutely nothing to do with this. I am deeply regretful at what I posted."

Prior to the Steelers' Week 3 game against the Chicago Bears on Sunday, they remained in the tunnel during the playing of the national anthem.

After the Steelers opted to not take the field for the anthem, Tomlin explained the decision, per Stephen J. Nesbitt of the Pittsburgh Post-Gazette:

"They chose to remove themselves from it. They were not going to be disrespectful of the anthem, so they chose not to participate. But at the same time many of them were not going to accept the words of the president. We decided to sit it out, to not take the field, to remove ourselves from it, to focus on playing football. Those were our intentions."

The Steelers' choice came after President Donald Trump commented on NFL players protesting during the anthem, according to ESPN.com's Kevin Seifert: "Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a bitch off the field right now. Out. He's fired! He's fired!'"

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Every NFL team had a demonstration of some kind related to the anthem in Week 3, including staying in the tunnel, kneeling or locking arms.

The Steelers fell 23-17 to the Bears in overtime and now sit at 2-1 on the season.