Nothing harmful was found, but suspicious packages delivered to the Cook County Building drew a massive emergency response Tuesday afternoon.
Five packages were mailed to county commissioners and Board President Todd Stroger.
An EMS Plan 1 was called at 118 N. Clark St., sending five ambulances and several fire vehicles to the scene. Perimeter streets were also closed as crews respond.
The Chicago Fire Department said suspicious material was found on the third floor and fifth floors, inside the mailboxes of several commissioners. One official opened an envelope and found a strange substance inside.
Authorities would not say whether the packages contained a letter, nor would they identify the substance, but did say it wasn't dangerous.