U.S. reassures Muslim-Americans

In a statement, the U.S. Department of Homeland Security said it was "doing all it can to protect the homeland from violent extremists."

"While we are not aware of any current, credible or active threat domestically, nor of any current information regarding obvious ties between the perpetrators in New Zealand and anyone in the U.S., the department is cognizant of the potential concerns members of Muslim American communities may have as they gather at today's congregational prayers," the DHS statement said.

"Communities with concerns should contact their local law enforcement agency, whom we are committed to supporting as they protect local mosques and reassure local community members," the statement added.

White House press secretary Sarah Sanders said the U.S. "strongly condemns" the "vicious act of hate." On Twitter, President Donald Trump slammed what he called the "horrible massacre," but did not directly refer to white supremacists or terrorist activity against Muslims.

Rising anti-Islam bigotry

For some Muslim American organizations, those comments were not enough, especially amid what they see as an intensifying wave of anti-Muslim rhetoric during Trump's tenure.

At a Friday press conference, the Council on American-Islamic Relations (CAIR) called for "national action to challenge growing Islamophobia, white supremacy and anti-immigrant bigotry."

"CAIR has reported an unprecedented spike in bigotry targeting American Muslims, immigrants and members of other minority groups since the election of Donald Trump as president and has repeatedly expressed concern about Islamophobic, white supremacist and racist Trump administration policies and appointments," the organization said.

White House officials strongly deny any link between Trump and Islamophobic incidents, noting the president has repeatedly condemned hatred and violence in all forms.

But as a presidential candidate, Trump called for the "total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what the hell is going on."

Though Trump eventually backed down from that proposal, he later surrounded himself with several senior advisers who had explicitly embraced anti-Islam views. Those advisers include former national security adviser Michael Flynn, who once tweeted that "Fear of Muslims is RATIONAL," and former chief strategist Steve Bannon, who has said the U.S. is the "wrong place" for "sharia-compliant" Muslims.