"A source in federal law enforcement told Fox Chicago that the case is similar to one that unfolded in New York yesterday" -- that is, May 21, when the Bronx synagogue plot was foiled. Bronx synagogue plot background [1] here. "Police Raid Apartment, 2 In Custody," from [2] MyFoxChicago, May 22 (thanks to [3] Pamela):

Glenda Johnson saw so many police and plain clothed federal agents on her block that she thought someone had been shot.

"The police was so crowded, you couldn't even walk past. They was in trucks, they was in cars, they was in regular cars. It looked like someone had killed someone," said Johnson.

That swarm of badges consisted of the FBI, Chicago Police and the Joint Terrorism Task Force. In their sights were two buildings on the 6300 block of North Artesian. People who live in a six flat there say the feds were very interested in its basement, specifically, two storage lockers....

“They was looking for someone who lives in this building. So I was like ‘what's the cause?’ They said ‘we don't want to say yet, but it's a life and death situation.’ I was like ‘wow,’” said Johnson.

A source in federal law enforcement told Fox Chicago that the case is similar to one that unfolded in New York yesterday.

Choi notes (via [4] Pamela) that the raid took place on the same street where a Muslim was arrested for threatening a Jewish school a few months ago.