Agents from the FBI, IRS and U.S. Department of Housing and Urban Development have conducted an after-hours search at Cleveland City Hall.

Spokespeople for the FBI and IRS have confirmed that agents went to City Hall after the building closed Wednesday night as part of a criminal investigation but wouldn't provide details about what agents were looking for at the building.

A Cleveland spokesman said Thursday that the search was part of an "ongoing investigation" and that the city is cooperating with federal authorities. He declined to say what the investigation concerns.

Cleveland.com has reported that agents didn't leave the building until after 11 p.m. Wednesday.