Thousands of people gathered in Chapel Hill to mourn three Muslim students killed by an anti-religion gunman who shot them in the head, rocking the tight-knit university town.

Friends and family poured onto the University of North Carolina campus to remember Deah Shaddy Barakat, 23, his new wife Yusor Mohammad, 21 and her 19-year-old sister Razan Mohammad Abu-Salha.

The three were allegedly killed by neighbour Craig Stephen Hicks, 46, whose Facebook page espoused his anti-religious views.