Officials on Wednesday evacuated an airport in Flint, Michigan, where a witness said he saw an officer bleeding from his neck and a knife nearby on the ground.

On Twitter, Michigan State Police say the officer is in critical condition and the FBI was leading the investigation.

The FBI is investigating the stabbing as a possible act of terrorism, NBC News is reporting.

Police confirmed to WOOD TV8’s NBC affiliate WEYI that an airport police officer, identified as Lt. Jeff Neville, was stabbed at the airport Wednesday morning. He is in stable condition, according to WEYI.

Authorities say a person of interest in the stabbing is in custody. NBC News reports that the Canadian born suspect yelled “Allahu Akbar” before stabbing the officer multiple times.

Bishop International Airport posted on Facebook that passengers were safe and were being told to check for flight delays or cancellations.

Ken Brown tells The Flint Journal he was dropping off his daughter at the airport and saw the officer bleeding from his neck. He says he saw a man detained by police and a knife on the ground.

“The cop was on his hands and knees bleeding from his neck,” Brown said. “I said they need to get him a towel.”

Cherie Carpenter, who was awaiting a flight to Texas to see her new grandchild, tells Flint TV station WJRT she saw the attacker being led away in handcuffs. She described the man in custody as appearing “blank, just totally blank.”

Airport and police officials didn’t immediately respond to messages from The Associated Press seeking comment.

Flint is about 50 miles northwest of Detroit.

BREAKING: Feds Investigating Attack on Officer at Flint Airport as Act of Terror; Attacker Yelled ‘ALLAH AKBAR’ – https://t.co/x0FKXYJ1mn pic.twitter.com/temdod9vZF

— Breaking911 (@Breaking911) June 21, 2017

(YWN Headquarters – NYC / AP)