The shooting deaths of three Muslims near the campus of the University of North Carolina here were followed Wednesday by alarm and debate about why a neighbor allegedly gunned them down and what role, if any, religion may have played.

Police said that initial indications suggested the shooting stemmed from "an ongoing neighbor dispute over parking," an assertion that was echoed by the suspected shooter's wife. But relatives of the victims insisted that the incident should be viewed as a hate crime.

As word of the shooting spread, so did unease at the possibility that the three were targeted for their religion. The hashtag #MuslimLivesMatter became a common refrain on Twitter as users expressed sorrow and anger at the possibility that the crime was religiously motivated as well as frustrations with what they saw as the media's failure to initially or thoroughly report what had happened.

The three victims were all young adults with ties to universities in the region, and two of them had gotten married just six weeks earlier: Deah Barakat, 23, was a second-year student at the University of North Carolina's School of Dentistry; his wife, Yusor Mohammad Abu-Salha, 21, was set to enroll there in the fall. The third victim was her 19-year-old sister, Razan, a student at nearby North Carolina State University in Raleigh.

"They were angels, just wonderful, beautiful people," Ayoub Ouederni, vice president of the UNC Muslim Student Association, said Wednesday. "They were all-American kids, just ordinary kids."

Police have arrested and charged Craig Stephen Hicks, 46, with three counts of murder. Hicks turned himself in to the Chatham County Sheriff's Office in nearby Pittsboro after the shooting.

Leading Muslim civil rights advocates called for police to address the possibility that the shootings Tuesday afternoon in a quiet condominium complex were a hate crime. But the Chapel Hill Police Department said it appeared, at least initially, that the shooting centered on an argument over parking, while also promising to investigate whether religion was a factor in the killings.

"Our investigators are exploring what could have motivated Mr. Hicks to commit such a senseless and tragic act," Chris Blue, the Chapel Hill police chief, said in a statement. "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."

Family members of the victims disputed the idea that it was simply an argument over parking. The father of Yusor and Razan Mohammad Abu-Salha said Wednesday that one of his daughters had previously told her family about Hicks having a problem with the way she looked.

"It was execution-style, a bullet in every head," Mohammad Abu-Salha, a psychiatrist in nearby Clayton, told the News and Observer in Raleigh. "This was not a dispute over a parking space; this was a hate crime. This man had picked on my daughter and her husband a couple of times before, and he talked with them with his gun in his belt. And they were uncomfortable with him, but they did not know he would go this far."

Hicks frequently criticized religion in his social-media postings. In a news conference Wednesday, Hicks's wife insisted that the shooting happened because of arguments over parking and not because of bigotry.

"I can say with my absolute belief that this incident had nothing to do with religion or [the] victims' faith but in fact was related to the long-standing parking disputes that my husband had with the neighbors," Karen Hicks said. She later added, "We were married for seven years, and that is one thing that I do know about him."

She said Craig Hicks had been attending school full time and was due to graduate from a paralegal program in the area this spring. An attorney for Karen Hicks said that the shooting highlighted the importance of improving access to mental health care but would not comment on whether Craig Hicks had a history of mental-health issues. Another of her attorneys said that Craig Hicks had a concealed-weapons permit.

Ouederni, of the Muslim Student Association, said relations between Muslims and other Americans in the Raleigh-Durham-Chapel Hill area had been very good.

"The reason everybody is so surprised is that it came out of nowhere," Ouederni said. "The community has co-existed peacefully for decades here. There have never been frictions. This just came out of the blue."

He said there had been "increasing Islamophobia in America" because of the rise of the Islamic State, but he said he had seen no evidence of that in North Carolina.

"We lost three Muslims last night, but we also lost three great Americans," Ouederni said.

Leaders from UNC, N.C. State, Duke University and North Carolina Central University spoke at a news conference Wednesday evening on the UNC campus and stressed that it was too soon to know whether the students were victim of a hate crime.

Imam Abdullah Antepli, an Islamic leader at Duke, said he had "full trust" that law enforcement officials would determine the killer's motives. But asked whether tensions had been higher recently, he said, "Absolutely."

"This incident immediately revealed the vulnerability of the Muslim community," he said. ". . . There are several hundred Muslim families in the greater Chapel Hill area, including myself, and we didn't send our children to school today. We wanted to know what was going on."

Jack Swanson, 25, a software developer, lives across the parking lot from the building where the shooting took place. "If it is a hate crime, it would be pretty unexpected in Chapel Hill," he said. "This is a college town. It's pretty open and accepting of everybody."

Swanson and other residents of the complex where the shooting occurred described it as a quiet area, a stretch of tall pine trees surrounding small buildings that mostly house graduate students. "You always see people out walking their dogs, and everybody's always friendly," he said.

People who lived there said Wednesday that there was plenty of parking and they could not imagine an argument over parking spaces. But Barakat had complained several months ago about a neighbor who had been harassing him about parking.

"He said he came to the house with a gun on his hip in a holster," Ali Heydary, a close friend of Barakat's, said Wednesday. "I thought they worked it out, because I never heard anything else about it."

Heydary said Barakat never suggested that the man was harassing him because of his religion, and Heydary said he had no evidence that Tuesday's shootings were motivated by religion. But, he said, "I don't think it was just over a parking space. No way. It had to be about something more."

Police arrived at the complex on Summerwalk Circle, not far from the UNC campus, shortly after 5 p.m. Tuesday in response to reports of gunfire.

"I just heard gunshots," a woman who called 911 told the dispatcher in a recording released Wednesday. She said she heard between five and 10 gunshots, adding, "I heard kids screaming."

All three victims were pronounced dead at the scene.

Craig Hicks made a brief court appearance on Wednesday morning, saying he understood the charges, according to The Associated Press. His probable-cause hearing was set for March 4, and he is being held without bond.

Nihad Awad, executive director of the Council on American Islamic Relations, called for police to address the speculation about Hicks's motive, citing "the brutal nature of this crime, the past anti-religion statements of the alleged perpetrator, the religious attire of two of the victims, and the rising anti-Muslim rhetoric in American society."

As the campus began mourning, details began to emerge about the three victims, painting a picture of young lives abruptly cut short.

The couple killed in the shooting were married in late December, a little more than six weeks ago, according to Yusor Mohammad Abu-Salha's Facebook account. On Monday, she changed her profile picture to show her dancing with her father at the wedding.

Barakat, whose family is of Syrian descent, had planned to take dental supplies to help Syrian refugees who have fled to Turkey, Heydary said. Bakarat had planned to go this summer; his wife had gone to deliver dental supplies to a Turkish town near the border last year. "She was just as passionate as he was," Heydary said.

Heydary said he and Bakarat were raising money to purchase dental equipment to help these refugees and had raised about $15,000 in donations by Tuesday. That number had topped $120,000 by Wednesday evening.

Attention turned Wednesday to the social-media profile of Hicks, who had frequently shared links about atheism on what appeared to be his Facebook page. One such post reads: "People say nothing can solve the Middle East problem, not mediation, not arms, not financial aid. I say there is something. Atheism."

Another post shared three weeks before the shooting depicted a loaded revolver, tucked in its holster, alongside five extra rounds.