No Colts players knelt during the anthem prior to the game in Indianapolis but the 49ers had more than 20 players kneeling with their hands over their hearts for the second straight week.
The Colts wore black T-shirts with the words "We Will" on the front and "Stand for equality, justice, unity, respect, dialogue, opportunity" on the back for the second week in a row as players stood with their arms locked during the anthem.
Pence, who was in Indianapolis as part of the celebration of Peyton Manning and his induction into the Colts' Ring of Honor, tweeted about leaving the game:
"I left today's Colts game because @POTUS and I will not dignify any event that disrespects our soldiers, our Flag, or our National Anthem."
About an hour later, President Donald Trump tweeted that Pence was acting in response to his instructions.
"I asked @VP Pence to leave stadium if any players kneeled, disrespecting our country. I am proud of him and @SecondLady Karen," Trump tweeted.
Pence, a former governor of Indiana, sent several follow-up tweets after his first one:
"At a time when so many Americans are inspiring our nation with their courage, resolve, and resilience ... now, more than ever, we should rally around our Flag and everything that unites us ... While everyone is entitled to their own opinions, I don't think it's too much to ask NFL players to respect the Flag and our National Anthem. ... I stand with @POTUS Trump, I stand with our soldiers, and I will always stand for our Flag and our National Anthem. ... We were proud to stand -- with all our @Colts -- for our soldiers, our flag, and our National Anthem."
Trump's position unified more NFL players to protest racial injustice before or during the anthem. He said during a political rally in Huntsville, Ala., on Sept. 22 that NFL owners should fire the players who knelt during the anthem.
"We're proud of our country. We respect our flag," Trump said to loud applause at the campaign event. "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!'"
Former San Francisco 49ers quarterback Colin Kaepernick drew national attention last season when he knelt during the national anthem as a protest against racial injustice. A number of players followed Kaepernick's lead by taking a knee during the anthem last year.
NFL players who have demonstrated during the national anthem have said they are protesting police brutality and racism, but not the flag or the anthem itself.