CHICAGO (AP) — Federal prosecutors on Monday charged a suburban Chicago man with trying to travel overseas to join the Islamic State group.

Members of the FBI's Joint Terrorism Task Force arrested Mohammed Hamzah Khan, a 19-year-old U.S. citizen from Bolingbrook, on Saturday evening at O'Hare International Airport, prosecutors said. Khan is charged with attempting to provide material support to a foreign terrorist organization, and a federal judge has ordered him held until a detention hearing Thursday.

According to prosecutors, Khan was trying to fly to Istanbul, Turkey, by way of Vienna, Austria, when law enforcement saw him go through security at O'Hare's international terminal. Agents then executed a search warrant at Khan's residence and found documents expressing support for the Islamic State group.

According to the criminal complaint, one page in a notebook had a drawing of what appeared to be an armed fighter with an Islamic State group flag and the words "Come to Jihad" written in Arabic.

FBI agents questioned Khan at the airport. On Monday, the slight, bearded Khan appeared in a federal court in orange jail clothes as he spoke with his attorney before the hearing started in his case.

There are about 12 Americans believed to be fighting in Syria right now, FBI Director James Comey said Thursday. There are more than 100 Americans who have either tried to go to Syria and were arrested, or went and came back to the U.S., Comey said without offering more details.