The FBI confirmed that it is investigating Wednesday's stabbing of a police officer in the state of Michigan as an "act of terrorism."

A 50-year-old Canadian citizen was detained after wounding the officer inside Bishop International Airport in Flint, Michigan, the FBI said.

 "We're investigating this incident today as an act of terrorism," FBI Special Agent David Gelios, who is in charge of the investigation into the attack, said.

Gelios also said that Canadian citizen Amor Ftouhi, 50, originally from Tunisia, had been arrested as a suspect in the attack and was charged with committing a violent act in an international airport.

He said that Ftouhi entered the US legally on June 16 and went to the airport on Wednesday morning.

According to the FBI's account of the incident, security camera footage shows Ftouhi standing with baggage at Bishop International Airport and then brandishing a 12-inch knife, yelling "Allahu Akbar" (God is great, in Arabic) and stabbing airport police officer Jeff Neville in the neck.

Neville, a 16-year veteran of the airport police, managed - despite his wound - to wrestle Ftouhi to the ground, but later underwent surgery.

State police said that the officer is now out of surgery and in stable condition.

Ftouhi is alleged to have shouted that the US had killed people in Syria, Iraq and Afghanistan.

Gelios said that an investigation is under way into the attack, noting that Canada is cooperating in assembling evidence with an eye toward determining what links Ftouhi might have with the US northern neighbor.

President Donald Trump has been briefed and is continuing to receive information on the attack, the White House said.

Meanwhile, the FBI said that the suspect is being questioned to determine the motive for the attack, although the agency added that with the information gathered to date it believes that this was an isolated incident and there is no credible evidence of any continuing danger to the community of Flint.

The attack occurred about 9:45 am on the second floor of the main airport terminal, which is Michigan's third largest with annual passenger traffic of about 800,000.

Police advised travelers intending to use the airport, which remained closed for most of the day after the attack, to contact their airlines to finalize their travel plans.