Police have arrested a gunman in the killing of three Muslims in the town of Chapel Hill in North Carolina, according to AFP.

The shooter, identified as Craig Stephen Hicks, 46, is being held in Durham County Jail on three counts of first-degree murder, the Chapel Hill News & Observer newspaper said.

It said the victims were identified as Chapel Hill residents Deah Shaddy Barakat, 23, his wife Yusor Abu-Salha, 21; and her sister, Razan Abu-Salha, 19, of Raleigh.

Hicks turned himself in, news reports said.

Police have not said what the motive of the shooting was. Police in Chapel Hill were not immediately available for comment, an AFP report said.

A report by British newspaper The Independent said the victims were found by police shot dead in their family house.

Yusor Abu-Salha and Barakat married in December 2014. Yusor, who was studying Human Biology at North Carolina State University (NCU), was to finish his studies this year. Abo-Salha recently changed her profile picture on Facebook to a photo from her wedding day dancing happily with her father.

Barakat, the murdered husband, was believed to be graduated from NCU dental collage, his last Facebook status on 30 January read, "Tonight we provided free dental supplies and food to over 75 homeless people in downtown Durham."

According to The Independent, Barakat used to volunteer and provide emergency dental care to children in Palestine.

The 19-year-old sister, Razan, was studying Architecture and Environmental Design at NCU. Razan was known for her love of photography, The Independent said.

Meanwhile, no news confirmed the family's nationality, but Barakat's father, Namee Barakat, on his Facebook page mentioned that the family is from war-torn Syria, specifically from Idlib province.

Twitter and Facebook users expressed their anger at the crime, claiming they were killed for being Muslims.

A photo from the alleged killer's Facebook page of a loaded gun were shared many times with comments like "posting a picture of a weapon he owns, it doesn't matter what US laws are. Had this been a Muslim, the media would have had a field day with such pictures!"

American and international media did not report the killing as soon as it took place but hours later when users on Twitter started to criticise the low amount of news coverage.

Users described the attack on the family as a "hate crime." Hicks defines himself on Facebook as an atheist and among the TV programmes he likes are The Atheist Experience and Criminal Minds.

His Facebook cover photo reads, "Of course I want religion to go away."

A hashtag of #ChapelHillShooting went to the top of Twitter trends, with users posting photos and videos of the victims. They showed them playing football matches or singing, as well as photos of Yusor and Barakat's recent marriage.

Twitter user Aseel Shami posted a cartoon by LATUFF of a man holding a camera and wearing a jacket with the slogans CNN, CBS, NBC, ABC and Fox News, while walking on three dead bodies on the ground.