The president and first lady Melania Trump visited victims of the Mandalay Bay shooting in a Las Vegas hospital on Wednesday.
One of the victims. Thomas Gunderson, posted a video of himself standing as Trump walked into his hospital room.
"This guy looks tough to me," Trump said as he shook Gunderson's hand.
The video went viral, with more than 17 million views on Facebook.
"I will never lie down when the President of this great country comes to shake my hand!" Gunderson wrote in his Facebook post. "There may be plenty of issues in this country but I will always respect my country, my president and my flag. Shot in the leg or not, I will stand to show my President the respect he deserves!"
Trump spent 90 minutes visiting the shooting victims, according to White House Spokeswoman Sarah Huckabee Sanders.
The massacre, which left 58 people dead and more than 500 wounded, is the worst mass shooting in modern U.S. history.
The Associated Press contributed to this story.