Fire crews were dispatched to the courthouse located in the 50 block of North Duke Street, to assist police at 10:29 a.m.
The courthouse was evacuated around 11 a.m.on Tuesday.
North Duke Street between Chestnut and King streets closed brief while crews investigated.Police are still on scene and the investigation is ongoing.
Although officials at the courthouse originally said it would remain closed for the rest of the day, Commissioner John Parsons' says evacuees were given the all clear to return.
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