DETROIT -- The man suspected of stabbing an officer at a Michigan airport Wednesday unsuccessfully tried to buy a gun in the U.S. before the attack, but he did buy a knife here, the FBI said on Thursday.

David Gelios, head of the FBI in Detroit, made the disclosure at a news conference. He did not elaborate.

Amor Ftouhi, 49, is charged with committing violence at an airport. Acting U.S. Attorney Dan Lemisch says more charges are coming in the days ahead. Ftouhi is in custody until a bond hearing Wednesday.

Amor Ftouhi is suspected of stabbing an officer at the Flint airport on June 21, 2016. U.S. Attorney's Office for the Eastern District of Michigan

Ftouhi, a dual citizen of Canada and Tunisia, is accused of stabbing airport police Lt. Jeff Neville after yelling "Allahu akbar," the Arabic phrase for "God is great."

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According to the FBI, Ftouhi said something similar to "you have killed people in Syria, Iraq and Afghanistan, and we are all going to die."

The attack Wednesday at Bishop International Airport in Flint, Michigan, is being investigated as an act of terrorism, but authorities have no indication at this time that the suspect was involved in a "wider plot," FBI Special Agent in Charge David Gelios said on Thursday.

A lawyer said Ftouhi, a Montreal resident, has some understanding of English, but is mostly fluent in French. He was born in Tunisia.

The lawyer said he's been in Canada for 10 years, has family in Tunisia and Switzerland, and is married and has three children. He was working on and off as a truck driver and last worked about two weeks ago, she said. He indicted no mental or physical health problems and no drug or alcohol use.

At his court hearing earlier Thursday, Ftouhi was ordered held until a detention hearing next week.

The FBI is still trying to determine Ftouhi's motive and how he came to be radicalized, reports CBS News' Paula Reid. His alleged statements during the attack suggest his motive could be a general grievance with the U.S. -- similar to Boston Marathon bombers Dzhokhar and Tamerlan Tsarnaev -- rather than a direct response to ISIS propaganda, Reid reports.

At this point, there is also no indication that he was on law enforcement radar, Reid reports.