CHICAGO (CBS) — An alleged plot to bomb a downtown Chicago bar apparently has been foiled, and a young man has been arrested, in a FBI undercover operation.

The U.S. Attorney’s office said Saturday that Adel Daoud, 18, of Hillside, attempted to detonate what he believed to be a car bomb in front of an unspecified bar somewhere in downtown Chicago Friday night.

LISTEN: WBBM Newsradio’s Dave Marsett reports

• Read The Complaint Against Daoud

Daoud was arrested after an undercover operation in which federal prosecutors say he developed attack plans, searched for a target and checked it out.

The U.S. Attorney’s Office says Daoud was closely monitored by undercover officers throughout the operation, and was offered several opportunities to change his mind and walk away from the supposed attack.

But he did not, and the undercover agents supplied the harmless dud explosives he allegedly attempted to detonate, the U.S. Attorney’s office said.

A woman who said she was Daoud’s sister denied the charges by telephone and said her brother would never do anything like that.

Neighbors also expressed shock at the charges against Daoud.

“It’s just a shocker, because you just never would have thought. His mindset didn’t seem to be that way at all,” Dorothy Leverson told reporters Saturday afternoon.

Neighbors said Daoud was a recent high school graduate.

The investigation began when agents found that Daoud had been sending around material – some of which he claimed to have written – about violent jihad and killing Americans, prosecutors said.

After undercover agents engaged him electronically for a while, one of the agents in June introduced Daoud to his purported cousin, who claimed to be an operational terrorist living in New York, prosecutors said. Daoud expressed an interest in meeting with the cousin – really an undercover FBI agent – and made a list of 29 targets in the Chicago area that he sought to blow up, prosecutors said.

The list included military recruiting centers, bars, malls and other assorted tourist attractions, prosecutors said.

Daoud allegedly then picked a downtown bar as his target and conducted research and surveillance on it. He justified killing civilians on the grounds that “you can’t really take these people as regular people. They’re like, more like robots” because they are “for the war on terrorism,” prosecutors said.

In choosing a bar as his target, he said a bar would have the largest number of people inside at night, and he could set up the explosives under cover of darkness, prosecutors said.

He also said such an attack “won’t kill any Muslims for sure . . . [a]nd if you do it’s their fault,” prosecutors said. Drinking alcohol is not permitted for observant Muslims.