Authorities are treating the stabbing of a police officer at an airport in Michigan as an act of terrorism.
The suspect, Amor Ftouhi, 50, shouted "Allahu Akbar" ("God is greatest" in Arabic) before knifing the officer in the back and neck, said officials.
Lieutenant Jeff Neville is in a stable condition in hospital after Wednesday morning's attack at Bishop International Airport in Flint.
Lt Neville helped take the suspect, a Canadian, into custody at the scene.
Security camera footage showed Mr Ftouhi loitering at the airport with baggage before pulling out a 12in (30cm) blade and carrying out the attack in a non-secured, public area.
Lt Neville was standing at the top of the escalators when he was approached from behind and knifed at shortly after 09:00 local time (13:00 GMT).
FBI agent in charge David Gelios told media the attacker exclaimed "Allah" and "you have killed people in Syria, Iraq and Afghanistan, and we are all going to die".
Lt Neville wrestled Mr Ftouhi to the ground, according to police.
The FBI said the suspect appeared to be a "lone wolf" attacker.
Authorities said Mr Ftouhi was "co-operative" during questioning and had expressed "hatred for the United States".
The accused is charged with an act of violence at an international airport that caused serious injury, and could face 20 years in jail.
Mr Ftouhi entered the US at Lake Champlain, New York, from Canada on 16 June, said the FBI.
Canadian media reported that police were carrying out a search of his home in Montreal and had made two arrests in connection with the knife attack.
Local television footage showed Canadian gendarmes leading away three women, their faces concealed by blankets, from the four-storey building where Mr Ftouhi reportedly lives.
Following the attack, the Flint airport was evacuated and additional officers were stationed at city hall, officials say.
Flint Mayor Karen Weaver said in a statement: "My thoughts and prayers are with all of our law enforcement officers who work to service and protect us each and every day.
"I want the public to know that several agencies are involved and working to ensure the situation is under control."
They are taking extra precautions just to be safe, she added.
Police asked mass transit officials to be on notice for any further potential incidents.
The mayor's chief of staff, Steven Branch, told local media there was extra police presence at the city's water treatment plant.
President Donald Trump has been briefed on the incident by his Homeland Security advisor, White House press secretary Sean Spicer told reporters.
Officials say the airport will remain closed until further notice.
About 800,000 passengers used the airport last year.