The website for Trump Towers, the luxury skyscraper in Manhattan owned by Republican presidential front-runner Donald Trump, went down for about an hour Friday after the hacker group Anonymous condemned Trump for his recent anti-Muslim comments, Reuters reported.

Anonymous, which frequently takes stands against governments and other powerful entities, tweeted that it caused the outage on

Trump frequently uses his 68-story skyscraper for his presidential-campaign activities and events. Two days before the website outage, an Anonymous member tweeted an image that shows the hacker trying to take down the Trump Towers website.

The attack on Trump’s website comes after he called for a temporary ban on Muslims entering the United States, a proposal that caused an international uproar. Anonymous warned the New York billionaire in a YouTube video posted Wednesday that it did not like his plan, which he proposed after the Dec. 2 mass shooting by a Muslim couple in San Bernardino, California. A message in the video’s description read, “Donald Trump think twice before you speak anything. You have been warned Mr. Donald Trump.”

While most politicians and many world leaders have condemned Trump’s remarks about Muslims, voters seem more split on his proposal. A poll released by NBC and the Wall Street Journal found that although 57 percent of adults disagree with Trump’s call to ban Muslims entering the U.S., 42 percent of Republicans agree with the idea.

Recent terror attacks in Paris and San Bernardino have also made Americans fearful that more are coming. Americans are more afraid of another terrorist attack than they have been at any time since the weeks immediately after 9/11, according to a New York Times/CBS poll released Thursday.

In the video from Anonymous, a speaker wearing a Guy Fawkes mask said that Trump’s ideas will help terrorist groups like the so-called Islamic State, which claimed responsibility for the Paris attacks and inspired the San Bernardino shooters. “This policy is going to have a huge impact,” the speaker in the video said. “This is what ISIS wants. The more Muslims feel sad, the more ISIS feels they can recruit them.”