The slayings of three young Muslims near the University of North Carolina tapped a deep well of fear and anger over bias toward American Muslims.

The hashtag #MuslimLivesMatter spread widely on Twitter.

When Chapel Hill police said a preliminary investigation indicated a parking dispute had triggered the shootings, several U.S. Muslim leaders said the brutal nature of the crime warranted a hate crime investigation from both federal and local law enforcement. The family of the victims joined the call for a hate-crime inquiry.

"How would we be dealing with this issue if the faith and ethnicity of the victims and perpetrator were switched, if a brown-skinned person went into the room of three white people and shot them?" said Dalia Mogahed, director of the Institute for Social Policy and Understanding, a think-tank that specializes in Muslim issues. "We're all just floored by the blatant double standard that we're seeing in both law enforcement and media coverage of the issue."

Many Muslims voiced outrage that the killings Wednesday had not drawn more media attention.

The victims were a newlywed couple, Deah Shaddy Barakat, 23, and Yusor Mohammad, 21, and Mohammad's sister, 19-year-old Razan Mohammad Abu-Salha. Craig Stephen Hicks, 46, was charged with three counts of first-degree murder in the shootings at the Chapel Hill condominium complex.

The father of the women, Mohammad Abu-Salha, told The News & Observer of Raleigh that Hicks had harassed his daughter and husband a couple of times before, and had a gun in his belt when he spoke with them. Abu-Salha said his daughter Yusor, who lived next door to Hicks, wore a Muslim head scarf and told her family a week ago that she had "a hateful neighbor."

"Honest to God, she said, 'He hates us for what we are and how we look,'" he told the newspaper.

Muslim Advocates, a civil rights organization based in California, urged U.S. Attorney General Eric Holder to open a federal inquiry into the homicides. "We cannot ignore the environment in which this incident took place," said Madihha Ahussain of Muslim Advocates.

The Council on American-Islamic Relations made a similar plea. Chapel Hill police Chief Chris Blue said, "We understand the concerns about the possibility that this was hate-motivated, and we will exhaust every lead to determine if that is the case."

Muslim groups planned vigils for the victims in North Carolina, New York, Virginia and elsewhere, while others organized a worldwide Quran reading as a memorial.

The reaction reflects the alarm many American Muslims feel in the face of anti-Muslim prejudice which has persisted since the Sept. 11 terror attacks, often spiking after terror attacks overseas.

Muslim communities in Georgia, Tennessee, Connecticut and other states have faced intense opposition when they've tried to build mosques. Several state legislatures have considered or approved laws banning the use of Islamic law in U.S. courts — measures motivated by fear that Muslims seek to take over the U.S. Last month, after a dispute at nearby Duke University over a plan for a Muslim call to prayer from the chapel bell tower, the campus Muslim center started receiving threats. The prayer call was moved.

Dustin Barto, editor of Muslim American magazine, based in Raleigh, North Carolina, said the killings could be both a parking dispute and a hate crime, noting the women victims were easy to identify as Muslim from their head coverings.

"If the individual had not been a clearly practicing religious person who could be identified by their religion, would it have gone to that level of violence? That has to come out in a trial." Investigators, he said, should "evaluate all the potential motives."