Murder charge in US beheading case

A man who allegedly beheaded a woman in the US after losing his job has regained consciousness and will face a charge of first-degree murder, police say.

Alton Alexander Nolen, the man who allegedly beheaded a woman on 25 September 2014 at Vaughn Foods distribution plant in Moore, Oklahoma (AAP)

A US man who was shot after authorities say he beheaded one woman and attacked another has regained consciousness.

Alton Nolen, 30, who has been interviewed by detectives, remains hospitalised in stable condition after Thursday's attack at the Vaughan Foods food processing plant in Oklahoma.

Police Sergeant Jeremy Lewis said that Nolen will be charged on Monday with first-degree murder and assault and battery with a deadly weapon, and may face federal charges.

Meanwhile, a spokesman for an Oklahoma City Islamic group said on Saturday that Nolen was a frequent worshipper at one of the group's mosques.

Islamic Society of Greater Oklahoma City director of information Saad Mohammed described Nolen as "a little weird".

"He was a nice, quiet, low-key guy," Mohammed said. "He acted a little odd."

But he added that Nolen's behaviour never raised any "red flags".

Mohammed said Nolen began worshipping at the mosque in May.

Police said Nolen was fired right before the attack, and that he drove from the company's human resources department to its main distribution centre.

He attacked Colleen Hufford with a knife in the administrative office area, eventually severing her head, according to police.

Nolen then repeatedly stabbed Traci Johnson before reserve sheriff's deputy and chief operating officer Mark Vaughan shot him, police said.

Johnson was treated for her injuries at the University of Oklahoma Medical Centre and released on Saturday, a medical spokeswoman said.

The police officer said Johnson was interviewed on Saturday.

Nolen was fired for "numerous reasons" involving "personnel issues," the officer said.

Police asked the FBI to help investigate Nolen's background after co-workers said he had tried to convert several employees to Islam and because of the nature of the attack, which followed a series of Islamic State videotaped beheadings in Syria.

Mohammed said Nolen had attended services where sermons condemned such attacks.

"In no way, shape or form did he represent Islam in this foolish act," he said.

FBI special agent in charge James Finch said in a statement the motive for the attack had not been determined.

"We don't have any reason to believe there is any danger to the area," Lewis said.

According to Oklahoma Department of Corrections records Nolen, who had a 2011 conviction for cocaine possession, served time in prison and was on probation for assault and battery of a police officer.

The records show Nolen has religious tattoos, including one referencing Jesus and one in Arabic that means "peace be with you".