Just after 2:15 p.m., Giannoulias said the Illinois Secretary of State Police received notice of a threat involving the Capitol building, and locked down, while police conducted a sweep of the building.
No information was immediately provided on the nature of the threat.
The lockdown was lifted sometime before 4 p.m., after police determined there was no danger.
Recorded messages reportedly played throughout the building, and some makeshift barricades were made inside some rooms.
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Other meetings carried on without interruption.