The motive behind a triple homicide at a university in Chapel Hill, North Carolina was an ongoing neighbourhood dispute over parking, police said.

Craig Stephen Hicks, 46, allegedly shot dead three Muslim students - identified as Deah Shaddy Barakat, 23, his wife Yusor Mohammad Abu-Salha, 21 and her sister Razan Mohammad Abu-Salha, 19 - before turning himself into police.

It was originally suspected that the killing was motivated by religion, due to a Facebook page bearing Hicks' name, accompanied by atheist slogans.

However, a police report said in a statement their preliminary investigation shows the fight over parking sparked the fatal shooting of the college students, AP reported.

Hicks is expected to make a first court appearance Wednesday morning. Police say he's been cooperative.