The Dirksen Federal Building in downtown Chicago is under lockdown Tuesday. The building was placed on lockdown shortly after 11 a.m., the FBI confirmed. The U.S. Marshals said a man armed with a knife tried to get past security in the building, but was stopped before he could.

A federal building in downtown Chicago has been under lockdown for several hours after a knife-wielding man entered the building

The Dirksen Federal Building in downtown Chicago was on lockdown Tuesday morning, according to the Federal Bureau of Investigation. As of 11:30 a.m., an emergency response was reported at the scene and the building was on lockdown,