Federal authorities have arrested an Illinois teenager on Saturday at a major airport in Chicago on suspicion of attempting to travel to the Middle East to join Islamic State, also known as ISIL or ISIS.

On Saturday at Chicago's O'Hare International Airport, the FBI arrested Mohammed Hamzah Khan, 19, an American who lived in Bolingbrook (located in the Chicago metro area), without incident. He appeared in court yesterday to face charges of "attempting to provide material support to a foreign terrorist organization."

Khan's family attended his first appearance in court, but issued no comment and asked for privacy. However, a CNN report noted that Khan's neighbors expressed shock over the news.

"Surprised, really surprised," said Steve Moore, who says he knew the family for about two years. "The kid was polite. I didn't expect anything like that in the least bit."

Neighbors in Bolingbrook also told a CNN affiliate that Khan graduated from the Farquaan Academy, an Islamic school located across from his house. Members from a local mosque described him as a nice, polite young man.

"He's the last person that we'd think that would happen to," said Bahauddin Ali Khan, a member of the mosque that Khan regularly attended.

The Department of Justice claimed that Khan planned to fly to Istanbul via Vienna. The department also contended that he planned to slip through the Turkish border to either Syria or Iraq, the same route where many potential ISIS recruits go through.

CNN has reported that Khan waived his Miranda rights during questioning at the airport and told FBI agents that a person he met online gave him the number of a contact to call once he made it to Turkey. Khan noted that contact would take him into ISIS territory.

According to an ABC News report, prosecutors claimed in a criminal complaint that Khan apparently wrote a letter to his family, which was found in his bedroom.

"My dear parents, there are a number of reasons I will be going to the blessed land of Shaam [Syria] and leaving my home," the letter said, according to the complaint. "We are all witness that the western societies are getting more immoral day by day. I do not want my kids being exposed to filth like this."

According to the complaint, Khan wrote in the letter that he couldn't stand the thought that his U.S. taxes were being used to kill his "Muslim brothers and sisters." He also noted that there was an obligation to "migrate" to ISIS-controlled territory.

A USA Today report noted that if Khan is convicted of the charges, he faces a maximum penalty of 15 years in prison and a $250,000 fine.