Craig Stephen Hicks was charged with three counts of first-degree murder after he drove himself over to Chatham County immediately after the shootings and surrendered to deputies in Pittsboro.
The students who were killed have been identified as 23-year-old Deah Shaddy Barakat of Chapel Hill, 21-year-old Yusor Mohammad Barakat of Chapel Hill, and 19-year-old Razan Mohammad Abu-Salha of Raleigh.
Sources told ABC News affiliate WTVD-TV that the victims were each shot in the head. Officers were first alerted at 5:11 p.m. Tuesday to a call of shots fired in the 200 block of Summerwalk Circle in the Finley Forest Condominiums. The complex is home to many UNC graduate students.
Family members said the Barakats had problems with Hicks, who was their next door neighbor, in the past.
On his Facebook page, Hicks describes himself as an "anti-theist" and posted statements condemning all religions. In one post, he asks "why radical Christians and radical Muslims are so opposed to each others' influence when they agree about so many ideological issues."
The statements prompted the Council on American Islamic Relations Wednesday to call on law enforcement to address a "possible bias motive" for the shootings.
"Based on 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, we urge state and federal law enforcement authorities to quickly address speculation of a possible bias motive in this case," said CAIR National Executive Director Nihad Awad.
Chapel Hill police said Wednesday that Hicks was cooperating with investigators and the initial investigation shows the shooting was motivated by an ongoing dispute over parking.
"Our investigators are exploring what could have motivated Mr. Hicks to commit such a senseless and tragic act. 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. Our thoughts are with the families and friends of these young people who lost their lives so needlessly," said Chief Chris Blue of the Chapel Hill Police Department.
Hicks was being held in the Durham County jail without bond. He was scheduled for a first court appearance Wednesday morning.
Deah Barakat was enrolled at the UNC School of Dentistry. His wife was completing her biology degree at NC State and planned to begin her dental studies at UNC this fall. They were recently married in December.
Razan was Yusor's sister. She attended NC State and was studying architecture and environmental design according to her Facebook page. She was visiting her sister at the time of the shooting. The women were both graduates of Athens Drive High School in Raleigh.
PHOTOS: Chapel Hill shooting claims lives of 3 students
Friends and family said Deah and Yusor had raised thousands of dollars to travel to Turkey to provide dental care to Syrian refuges.
In a fundraising video, Deah asks people to contribute to a trip for 10 dentists.
"These kids don't have access to the same health care as us," he says. "Their prolonged pain can easily be taken care of by what we do."
Click for the YouTube fundraising video
A Facebook page set up to remember the victims said funeral arrangements were pending. Called "Our Three Winners," it urges people to remember the "beautiful ways these three people have touched your lives."
"Please rely on each other and remember these beautiful souls in your happy thoughts. Their faith meant a lot to them, and it is in fact what helps us all feel at peace with the tragedy of their murder," it said.
A vigil for the victims was set for 7 p.m. Wednesday at Chapel Hill's Peace and Justice Plaza on East Franklin Street.