CHICAGO (CBS) — Federal agents on Thursday raided the offices of Chicago Alderman Ed Burke.

The doors were shut and the windows were covered in paper on Thursday at the City Hall and ward offices of Chicago’s longest-serving Alderman, Ed Burke.

That’s because federal agents were busy inside.

The brown paper covering the windows came down around 2:00 Thursday afternoon. The lights have been out ever since. The FBI confirmed they executed search warrants at Burke’s Gage Park office and his office downtown. But that’s all the agency will say.

“I’ll fully cooperate and I don’t think they’ll find anything amiss,” Burke said when confronted by CBS 2’s Lauren Victory outside his home Thursday night.

A number of computer hard drives, several boxes stacked on top of one another, and at least one computer monitor. They were among the items removed by a half dozen law enforcement agents from the back door of Ald. Ed Burke’s 14th Ward office.

Burke is often referred to as Chicago’s most powerful alderman. The windows on the 51st Street side of Burke’s headquarters were taped shut with thick brown paper and hand-scribbled signs reading “office closed.”

Neighbor Jeronimo Segura said he noticed law enforcement vehicles as early as 8:30 Wednesday morning. Francisco Ortega from the bakery next door witnessed activity around midnight.

“I see two agents they came in a car like that one they came and knock on the door,” Ortega said.

At one point an agent who identified himself as FBI removed an odd florescent green rod from his vehicle and took it inside. A sign in the window was marked Chicago Police Narcotics Task Force.

The FBI confirmed agents were executing search warrants at multiple locations connected to the alderman. They were most likely among the dozen or so agents who exited tight lipped from the front door, driving off after spending most of the morning and afternoon inside.

The exact reason for the raids is still unknown.

Ed Burke is not only the longest serving alderman in Chicago history. He’s arguably the most powerful alderman in Chicago history. Burke himself admitted he’s under the federal microscope.

In comments released late Thursday afternoon, Ald. Ed Burke acknowledged the current federal probe is not his first time under investigation.

“So once again we will be cooperating fully and I am completely confident that at end of the day nothing will be found amiss.”

City Hall workers arrived at work Thursday morning and found the door of Ald. Ed Burke’s office covered in brown paper. Federal agents inside, presumably examining records of the powerful Finance Committee chairman.

Ed Burke has spent 50 of his 74 years in City Council, representing Chicago’s Southwest Side 14th Ward and is chair of the Finance Committee, holding a tight grip on spending legislation.

Alderman Howard Brookins, who has a City Hall office next to Burke’s, expressed surprise and support.

“I don’t care to speculate about anything,” said Brookins, who represents the 21st Ward. “I wish Ald. Burke the best. He’s been a great friend and mentor, leading me in the right direction with respect to legislation.”

He’s won reelection a record 13 times. But Burke is perhaps facing his toughest battle ever. Targeted by allies of Cook County Commissioner Jesus Garcia, who complained Burke was out of touch with his Hispanic-majority district.

Brookins said he was curious about the timing of the raid.

“It was shocking to me is to how or why something like this would happen some 90 days before an election,” Brookins said.

And similar thoughts expressed by Burke’s brother, Illinois State Representative Dan Burke (D-Chicago.) On Thursday, he served his final day in Springfield after his defeat in this year’s primary.

“I’d be suspicious. He’s seeking reelection. The timing you think about and wonder.” said Burke. “I know my brother’s character and service. I know who he is. I have no question, no concern about wrongdoing on his part.”

Records from Burke’s office were subpoenaed by federal investigators back in 2012. Records regarding the city’s workers compensation program, which Burke controls.

The FBI had a one sentence statement about Thursday’s activity: “Our agents are executing warrants at multiple locations today. We have no further comment.”

RELATED: A Look At Alderman Burke’s Business Dealings, Including Work For President Trump