HILLSIDE, Ill. (AP) — Undercover FBI agents arrested an 18-year-old American man who tried to detonate what he believed was a car bomb outside a downtown Chicago bar, federal prosecutors said Saturday.

Adel Daoud, a U.S. citizen from the Chicago suburb of Hillside, was arrested Friday night in an undercover operation in which an agent pretending to be a terrorist provided him with a phony car bomb and watched him press the trigger, prosecutors said.

The U.S. Attorney's Office in Chicago, which announced the arrest Saturday, said the device was harmless and the public was never at risk.

Daoud is charged with attempting to use a weapon of mass destruction and attempting to damage and destroy a building with an explosive. He remains in custody pending a detention and preliminary hearing set for Monday in federal court.

A person who answered the phone Saturday at the home where Daoud and his family live and identified herself as his sister, Hiba, declined to discuss Daoud, the family or the arrest.

"We don't even know anything. We don't know that much. We know as little as you do," she said. "They're just accusations. ... We'd like to be left alone."

Later Saturday, no one answered the door of the family's two-story home, which had a well-kept garden in the yard and a basketball hoop in the driveway. The house faces a Lutheran church; a Greek Orthodox church also is nearby.

Next-door neighbor Harry Pappas said he was shocked by the arrest, calling Daoud's parents "wonderful" people and him a quiet boy who played basketball in the driveway with friends.

"I heard maybe he had a little trouble in school," Pappas said. "He was quiet, didn't talk much, but he seemed like a good kid."

Pappas said Daoud spent a lot of time at home and that months would go by sometimes before the teen would surface.

"But I was never suspicious," he said.

Then on Friday night, a dozen unmarked cars drove up to the family's house and several agents went inside, Pappas said.

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The FBI began monitoring Daoud after he started using an email account to get and distribute material about violent jihad and the killing of Americans, prosecutors said.

In May, two undercover FBI agents contacted Daoud in response to the material and exchanged electronic messages with him in which he expressed an interest in violent jihad in the United States or abroad, according to an affidavit by an FBI special agent.

Prosecutors say one of those agents introduced Daoud to a third undercover agent who claimed to be a terrorist living in New York.

Over the summer, the third agent and Daoud met six times in the suburb of Villa Park and exchanged messages, the affidavit said. Daoud then set about identifying 29 potential targets, including military recruiting centers, bars, malls and tourist attractions in Chicago, the document said.

He is accused of settling on a downtown bar and conducting surveillance on it using Google Street View and visiting the area in person to take photographs.

Describing the target to the agent, Daoud said it was also a concert venue by a liquor store, the affidavit says.

"It's a bar, it's a liquor store, it's a concert. All in one bundle," the document quotes him as saying. It said he noted the bar would be filled with the "evilest people ... kuffars." Kuffar is the Arabic term for non-believer.

The affidavit said that shortly after 7 p.m. Friday, Daoud met with the undercover agent in Villa Park and they drove to downtown Chicago, where the restaurants and bars were packed. They entered a parking lot where a Jeep Cherokee containing the phony bomb was parked, the document says.

Daoud drove the vehicle and parked it in front of the bar, then walked a block away and attempted to detonate the device by pressing a triggering mechanism, the affidavit says. He was then arrested.

Court documents don't identify the bar.

The FBI has used similar tactics in other counterterrorism investigations, deploying undercover agents to engage suspects in talk of terror plots and then provide fake explosive devices.

In a 2010 case, a Lebanese immigrant took what he thought was a bomb and dropped it into a trash bin near Chicago's Wrigley Field. In a 2009 case, agents provided a Jordanian man with a fake truck bomb that he used to try to blow up a 60-story office tower in Dallas.

Prosecutors said Daoud was offered several chances to change his mind and walk away from the plot.

The affidavit said Daoud was active in jihadist Internet forums and was accessing articles written by Anwar al-Awlaki, the U.S.-born radical cleric who became a key figure in the Yemen-based al-Qaida offshoot known as al-Qaida in the Arabian Peninsula.

Al-Awlaki was killed in a U.S. drone strike in Yemen last year.

The FBI says he also was searching online for information on making bombs and reading "Inspire," the English-language online magazine published by Al-Qaida in the Arabian Peninsula.

In his conversations with the undercover agent, Daoud explained his reasons for wanting to launch an attack, saying the United States was at war "with Islam and Muslims," the affidavit said.

According to the document, he said he was trying to recruit others and that he was confronted by leaders of his mosque who warned he should stop talking about jihad. The affidavit said Daoud's father also had been informed that Daoud was debating jihad and told Daoud to stop talking about it.

Daoud also told the agent he wanted an attack that would kill many people, the document said.

"I want something that's gonna make it in the news," he said, according to the affidavit. "I want to get to like, for me I want to get the most evil place, but I want to get a more populated place."

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Keyser reported from Chicago.

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Follow Michael Tarm at www.twitter.com/mtarm .