WASHINGTON (Reuters) - Leaders of an ad hoc group of protesters enraged by Republican Donald Trump’s election as president of the United States vowed on Wednesday to disrupt his inauguration this week by blocking public access to the event.

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The DisruptJ20 protest group said it will send groups of demonstrators to the dozen entrances to the grassy National Mall where hundreds of thousands of people are expected to gather to watch Trump, who has never before held public office, be sworn in as president on the steps of the U.S. Capitol on Friday.

“We believe that it’s our role and the role of any people with conscience to try to disrupt this inauguration and have a massive showing of resistance on that day,” Samantha Miller, a DisruptJ20 organizer, said at a news conference.

The U.S. Secret Service and Washington police are expecting some 900,000 people to pack into the area between the Capitol and White House on Friday to view the swearing-in and will have thousands of uniformed officers on site.

Trump has angered many on the left with demeaning comments about women, immigrants and Muslims, a vow to repeal the sweeping healthcare reform law known as “Obamacare” and plans to build a wall along the U.S.-Mexico border.

His supporters admire Trump’s experience in business, including as a real estate developer and reality television star, and view him as a brash problem-solver.

Miller said DisruptJ20 will be sending groups of about 100 protesters to block each of the dozen security checkpoints for people entering the inaugural festivities.

“There will definitely be interactions with law enforcement that day, no doubt,” Miller said.

Washington’s Metropolitan Police Department declined to comment on the group’s plans.

“We support everyone’s First Amendment right to peaceably protest,” a spokeswoman said in an email, referring to the amendment to the U.S. Constitution that protects the right to free expression.

About 3 square miles (nearly 8 square km) of central Washington will be in a security cordon that will include roadblocks, street barricades and about 3,000 extra police, federal officers and 5,000 National Guard troops.

The inaugural parade down Pennsylvania Avenue will pass the Trump International Hotel, a rallying point for protesters since the election.

A man set himself on fire late on Tuesday outside the hotel, in what he told NBC 4 television was an anti-Trump protest. Police said he was taken to a hospital for treatment and had no details on his condition.