Ken Frazier, CEO of drug manufacturer Merck & Co Inc., set off a growing exodus from President Donald Trump’s manufacturing advisory council following weekend violence at a rally of white supremacists in Charlottesville, Virginia, that claimed the life of a counter-protester and injured 19.

After the rally turned deadly on Saturday, Trump first said that many sides were to blame. As criticism and political pressure mounted against him for not singling out white supremacists, Trump followed up Monday with a statement denouncing neo-Nazis and the Ku Klux Klan as criminals and thugs.

For Frazier, it was too late. One of just a handful of black leaders of Fortune 500 companies, Frazier was the first to leave Trump’s American Manufacturing Council following the initial response by the commander-in-chief, BBC reported.

The manufacturing council is a group of business leaders who advise the president on “how best to promote job growth and get Americans back to work again.”

So far, three more council members have resigned including Intel CEO Brian Krzanich, Under Armour CEO Kevin Plank, and Alliance for American Manufacturing President Scott Paul.

I'm resigning from the Manufacturing Jobs Initiative because it's the right thing for me to do.

— Scott Paul (@ScottPaulAAM) August 15, 2017

Frazier said he left the advisory council because of the president’s reaction after the violence between white supremacists and counter protesters, Reuters reported. He said he saw the need to “take a stand against intolerance and extremism.”

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pic.twitter.com/a1PNQZism5

— Merck (@Merck) August 14, 2017

Trump called on pharmaceutical companies in January to reduce “astronomical” drug prices.

In a tweet, Trump responded to Frazier’s resignation, saying, “Ken Frazier of Merck Pharma has resigned from President’s Manufacturing Council, he will have more time to LOWER RIPOFF DRUG PRICES!”

Later, Trump attacked Merck in a tweet, describing Merck as “a leader in higher & higher drug prices while at the same time taking jobs out of the U.S. Bring jobs back & LOWER PRICES!”

That smile when a negro thinks he is going to get something for bootlickin' but ends up getting stuck. pic.twitter.com/CFmMCZdoVs

— Jamarlin Martin (@JamarlinMartin) August 15, 2017

Are CEO's quitting Trump for business + reputation reasons or moral conviction?Why was that negro Frazier gigglin' with Trump in first place

— Jamarlin Martin (@JamarlinMartin) August 15, 2017

The son of a janitor, Frazier joined Merck as general counsel of one of the drugmaker’s subsidiaries in 1992, working his way up to CEO of the company in 2011, according to Reuters.

As the company’s top lawyer, he steered Merck through litigation over Vioxx, a widely used painkiller that was withdrawn in 2004 after being linked to heart attacks.

Frazier made political contributions during the 2016 election to both Republican and Democratic members of Congress but not to presidential candidates.

Merck’s political action committee, funded through employee donations, made $1.1 million-plus in candidate contributions in the 2016 campaign, according to documents filed with the Federal Elections Commission.

Frazier and the other three company heads are not the first to resign from a presidential advisory council. Others who have stepped down in protest of Trump’s policies include former Uber CEO Travis Kalanick, who left the Business Advisory Council in February over the Trump administration’s immigration policies. Tesla CEO Elon Musk and Walt Disney CEO Robert Iger left the President’s Strategic and Policy Forum in June after Trump said he would withdraw from the Paris climate accord. Musk also left the manufacturing council, BBC reported.

Many CEOs have challenged the White House over immigration, climate treaty, trade agreements, tax and regulatory issues. Why didn’t more of them come out in support of Frazier, asked Jeffrey Sonnenfeld, senior associate dean for leadership studies at Yale School of Management:

“Crises are tests of character … but the relative silence of much of the U.S. business community (was) most noteworthy,” Sonnenfeld said in a Fortune commentary. “A seat at table may be great if they use their voices. Sitting there as PR props or wallpaper is something else. The 2017 Edelman Trust Barometer identifies CEOs as now some of the most trusted sources, with public officials and the clergy dropping. They must use that precious bully pulpit.”

Frazier has been one of the most outspoken critics of abusive drug pricing, Sonnenfeld said. Calling out drug price offenders by name, Frazier has worked with his trade association to help identify abuses:

Frazier is the epitome of the American Dream. He grew up surrounded by gang violence in a tough North Philadelphia community. Inspired by his hardworking father…and revered Supreme Court Justice Thurgood Marshall, Frazier became a champion of justice on many levels. A Harvard-trained lawyer, he defended wrongly accused individuals and institutions. He helped his mentor Roy Vagelos donate the drug Mectizan, which cures river blindness and is consumed by battles against society’s most vexing diseases.

Source: washingtonexaminer.com

Fortune, reached out to all sitting CEOs on the president’s manufacturing council as well as the presidents of the AFL-CIO and Alliance of American Manufacturing, asking for a response to the weekend’s events and whether they planned to remain a member of the group.

Here are some of the answers, according to Fortune:

Richard Trumka, AFL-CIO:

The AFL-CIO has unequivocally denounced the actions of bigoted domestic terrorists in Charlottesville and called on the president to do the same. We are aware of the decisions by other members of the President’s Manufacturing Council, which has yet to hold any real meeting, and are assessing our role. While the AFL-CIO will remain a powerful voice for the freedoms of working people, there are real questions into the effectiveness of this council to deliver real policy that lifts working families. (Attributed to Trumka.)

Denise Morrison, Campbell Soup
The reprehensible scenes of bigotry and hatred on display in Charlottesville over the weekend have no place in our society. Not simply because of the violence, but because the racist ideology at the center of the protests is wrong and must be condemned in no uncertain terms.
Campbell has long held the belief that diversity and inclusion are critical to the success of our business and our culture. Our commitment to diversity and inclusion is unwavering, and we will remain active champions for these efforts.
We believe it continues to be important for Campbell to have a voice and provide input on matters that will affect our industry, our company and our employees in support of growth. Therefore, Ms. Morrison will remain on the President’s Manufacturing Jobs Initiative.

Michael Dell, Dell
While we would not comment on any member’s personal decision, there’s no change in Dell engaging with the Trump administration and governments around the world to share our perspective on policy issues that affect our company, our customers and our employees.

Andrew Liveris, Dow Chemical 
I condemn the violence this weekend in Charlottesville, Virginia, and my thoughts and prayers are with those who lost loved ones and with the people of Virginia. In Dow there is no room for hatred, racism, or bigotry. Dow will continue to work to strengthen the social and economic fabric of the communities where it operates – including supporting policies that help create employment opportunities in manufacturing and rebuild the American workforce. (Attributed to Liveris.)

Bill Brown, Harris Corp.
A Harris spokesperson said he was “not able to get a response for you.”

Mark Sutton, International Paper
International Paper strongly condemns the violence that took place in Charlottesville over the weekend – there is no place for hatred, bigotry and racism in our society. We are a company that fosters an inclusive workforce where all employees are valued and treated with dignity and respect. Through our participation on the Manufacturing Jobs Council, we will work to strengthen the social and economic fabric of communities across the country by creating employment opportunities in manufacturing.

Marillyn Hewson, Lockheed Martin
We do not have a comment.

John Ferriola, Nucor
At Nucor, we condemn the violence that occurred this past weekend in Charlottesville and reject the hate, bigotry, and racism expressed at the demonstration.
As North America’s largest steel producer, Nucor has engaged with several administrations to work on policies that help strengthen the U.S. manufacturing sector and provide opportunities for American workers. We believe a strong manufacturing sector is the backbone of a strong economy, and we will continue to serve as a member of the White House Manufacturing Jobs Initiative. (On behalf of Ferriola.)

Kevin Plank, Under Armour
I joined the American Manufacturing Council because I believed it was important for Under Armour to have an active seat at the table and represent our industry. We remain resolute in our potential and ability to improve American manufacturing. However, Under Armour engages in innovation and sports, not politics.
I am appreciative of the opportunity to have served, but have decided to step down from the council. I love our country and our company and will continue to focus my efforts on inspiring every person that they can do anything through the power of sport which promotes unity, diversity and inclusion. (Attributed to Plank.)

Jeff Fettig, Whirlpool
Whirlpool Corp. believes strongly in an open and inclusive culture that respects people of all races and backgrounds. Our company has long fostered an environment of acceptance and tolerance in the workplace. The company will continue on the Manufacturing Jobs Initiative to represent our industry, our 15,000 U.S. workers, and to provide input and advice on ways to create jobs and strengthen U.S. manufacturing competitiveness.

Brian Krzanich, Intel
Earlier today, I tendered my resignation from the American Manufacturing Council. I resigned to call attention to the serious harm our divided political climate is causing to critical issues, including the serious need to address the decline of American manufacturing. Politics and political agendas have sidelined the important mission of rebuilding America’s manufacturing base. (Attributed to Krzanich)

CEOs who did not respond to Fortune as of the time of writing included: 3M’s Inge Thulin, Boeing’s Dennis Muilenburg, Corning’s Wendell Weeks, Dana’s Jim Kamsickas, Johnson & Johnson’s Alex Gorsky, Newell Brands’ Michael Polk, Timken’s Rich Kyle, and United Technologies’ Greg Hayes.