Libraries in Chicago and surrounding suburbs were closed Tuesday after receiving bomb threats.

An employee at the Harold Washington Library Center, 400 S. State St., received an anonymous email saying that there was a bomb inside the building, Chicago police said. A bomb squad and canine units were sent to do a sweep of the building around 3:50 p.m. but did not find any sign of a threat.

Library patrons were unaware that a threat had been made against the building.

Similar threats were made at libraries in surrounding suburbs.

Officers responded to a call of a bomb threat at the Addison Public Library, 4 Friendship Plaza, about 2 p.m. As a precaution, all village buildings and the library were evacuated and closed to the public. The DuPage County Bomb Squad was called to search the building and determined the threat was unfounded.

Aurora police evacuated all three of the city’s public libraries and shut down surrounding roads after receiving a similar threat through an “online source” just before 3 p.m. The libraries are located in the 100 block of South River Street, the 500 block of South Eola Road and the 200 block of South Constitution Drive.

Around 3:45 p.m., the Evanston Public Library, 1703 Orrington Ave., also received a bomb threat, and the Cook County Sheriff’s Bomb Squad was sent to evacuate the building.

Lynn Sweet/Sun-Times

The threats came as Illinois Secretary of State Alexi Giannoulias testified at a Senate hearing Tuesday about the state’s first-in-the-nation ban against bans. The bill was signed by Gov. J.B. Pritzker on June 12.