Young people from the Husseini Islamic Center in Sanford, Fla., lay flowers Tuesday at a makeshift memorial in Orlando for the victims of the nightclub massacre. (Drew Angerer/Getty Images)

The Council on American-Islamic Relations had planned to hold a news conference Tuesday unveiling a report on Islamophobia, including the rise of “Muslim-free” businesses, anti-Muslim rallies by armed protesters, direct attacks on Muslims and the vandalism of mosques.

Then Orlando happened — an American Muslim slaughtered 49 people in a gay nightclub. CAIR officials realized they needed to hold off on their report and postpone the news conference, in part because the country should be focusing on homophobia and not Islamophobia.

But then came Donald Trump. In an incendiary speech Monday in New Hampshire, Trump described American Muslims in sweeping, harsh terms, depicting them as a kind of enemy within, prone to radical ideology and guilty of harboring terrorists.

The presumptive Republican presidential nominee said the terrorist attack in Orlando would never have happened if the gunman’s parents had not been allowed to emigrate from Afghanistan: “The bottom line is that the only reason the killer was in America in the first place was because we allowed his family to come here.”

Trump’s speech had a recurring theme: The enemy is already inside the gates, and current U.S. leaders are too fixated on political correctness to do anything about it, or don’t really want to stop it, and can’t even say the words “radical Islam.” Syrian refugees, allegedly fleeing war, may be terrorists in disguise — “a better, bigger, more horrible version than the legendary Trojan horse ever was,” Trump said.

CAIR officials and other American Muslim leaders were beside themselves Tuesday.

“It’s an effort to demonize, stigmatize a particular minority faith that’s already under siege to gain some political advantage over his opponent. It’s really despicable,” said CAIR spokesman Ibrahim Hooper.

Corey Saylor, another CAIR spokesman, said Trump is spreading false information when he says Muslims don’t report suspicious people in their midst. Saylor said he personally gave the FBI the identity of someone who possibly had become radicalized and that the person was later arrested.

Saylor’s wife was born in Afghanistan — like the Orlando killer’s parents — and used to throw rocks at Soviet tanks during the Soviet occupation of her country.

“There are a lot of Afghans in this country; many of them fought the communists back during the Soviet invasion era,” he said. “I think it’s a tremendous disservice to all of them, that we have converted them from the anti-communist fighters that they were to being a threat to this nation.”

Yasir Qadhi, dean of al-Maghrib Institute and a professor at Rhodes College in Memphis, did not mince words: “Trump is a racist demagogue rallying hatred to win an election. He’s taking advantage of a tragedy for his own political gains.”

Tayyib Rashid, a U.S. military veteran who tweets under the handle @MuslimMarine, said the candidate’s divisive rhetoric is a form of hate speech and ultimately serves the purposes of radical Islamists. He said he wished more people understood the contributions that Muslims make to the United States. “It’s unfortunate that the first time many people were introduced to Islam was 9/11. The first impression is the last impression,” he said.

President Obama also reacted vociferously Tuesday to Trump’s remarks on Muslims and defended his reluctance to use the term “radical Islam.” He said there is no “magic” to those words and that everyone knows whom the nation is fighting. He rejected Trump’s implicit demand to scrutinize American Muslims more closely than other citizens.

“Where does this stop? The Orlando killer, one of the San Bernardino killers, the Fort Hood killer — they were all U.S. citizens. Are we going to start treating all Muslim Americans differently? Are we going to start subjecting them to special surveillance?” Obama asked .

In his speech Monday, Trump suggested that Muslims in Southern California had had information about the husband-and-wife terrorist team that attacked an office party in December, killing 14 people: “They knew the people in San Bernardino were bad. But you know what? They didn’t turn them in. And you know what? We had death and destruction.”

Trump did not say who “they” were. The FBI has produced no evidence that anyone in the San Bernardino terrorists’ family — including the gunman’s mother, who lived with the couple — had advance knowledge of the attack. Only one person faces charges in the case, a man named Enrique Marquez, a convert to Islam who authorities say plotted in 2011 with gunman Syed Rizwan Farook to conduct a terrorist attack.

In Florida, meanwhile, attention turned Tuesday to the Orlando gunman’s wife, Noor Z. Salman. The FBI is trying to determine whether she had advance knowledge of the attack. A law enforcement source said she accompanied attacker Omar Mateen on one trip that appeared to be a “reconnaissance” of the Orlando nightclub.

Muslim cooperation with law enforcement has increased in recent years, said Charles Kurzman, a sociology professor at the University of North Carolina at Chapel Hill and co-director of the Center for the Study of the Middle East and Muslim Civilizations.

But, Kurzman added, extremists are typically isolated and hard to detect. They do not attend mosque regularly. They are usually estranged from their communities and often have mental illnesses.

“Radicalization happens online, and the Muslim community should not be blamed for the most marginal numbers of their community,” he said.

Kurzman published a study in February that counted 81 American Muslims being involved in extremists plots in 2015, the highest number in any year since the terrorist attacks of Sept. 11, 2001. A majority of those individuals either traveled to Syria, or sought to travel there, to join militant groups. Since 9/11, the study found, a total of 344 American Muslims had been involved in extremist plots, half of them involving targets overseas, and 40 percent here at home.

The Orlando gunman did not appear to have been devout. He did not dress conservatively or let his beard grow out. He attended a local mosque only sporadically. Some acquaintances have described him as gay and as a regular patron of the Pulse nightclub that he chose for his rampage.

Although Trump in his speech spoke of Muslims as a kind of monolithic community, they are in fact an extremely diverse demographic, coming from many ethnicities and ancestral countries. The precise number of Muslims in the United States is difficult to estimate, but CAIR goes with a figure of 6 million to 7 million, which equates to about 2 percent of the U.S. population. An estimate by the Pew Research Center is about 3.3 million U.S. Muslims.

A Pew national survey in 2011 showed that 61 percent of U.S. Muslims were “very” or “somewhat” worried about the rise of Islamic extremism across the country — a figure only modestly lower than the general public’s 73 percent response to that question.

About half the Muslims in the Pew survey said they thought Muslim leaders had not been sufficiently outspoken in denouncing extremists. More than 2 in 5 respondents said they had experienced discrimination of some kind, including being viewed with suspicion (28 percent), called offensive names (22 percent) or singled out for airport screening (21 percent). Six percent said they had been physically threatened or attacked.

CAIR’s research has documented a spike in anti-Muslim incidents at mosques after the terrorist attacks in Paris and San Bernardino last fall, with 17 incidents in November and another 17 in December.

After the Orlando massacre, some Muslim communities are reportedly preparing for a backlash.

The Islamic Community Center of Phoenix said it has received hateful emails since Sunday’s attack, according to Reuters. And in Orlando, police have patrolled the neighborhood surrounding the Islamic Center, and the center plans to hire extra security at night.