CHAPEL HILL, N.C. — It was a little after 5 p.m., a quiet time in a quiet neighborhood, before many people had returned home from work on Tuesday, when two women called 911 to report multiple gunshots and screams echoing through a condominium complex here near the University of North Carolina.

By the time the police arrived, three people were dead — a newlywed couple and the woman’s sister. They were young university students, Muslims of Arab descent, and high achievers who regularly volunteered in the area. A neighbor, a middle-aged white man, was missing — then under arrest and charged with three counts of murder.

The victims’ families described it as a hate crime. The police said that the shooting appeared to have been motivated by “an ongoing neighbor dispute over parking,” but that they were investigating whether religious hatred had contributed to the killings.

“To have him come in here and shoot three different innocent people in their head — I don’t know what kind of person that is,” said Namee Barakat, the father of the male victim, Deah Shaddy Barakat.