A park official says a white powder found in a balloon near the Liberty Bell in Philadelphia was flour.
The balloon was found Thursday inside the building that houses the Liberty Bell. The Liberty Bell Center and part of a street next to it were evacuated as a precaution.
Independence National Historical Park spokeswoman Jane Cowley says multiple tests determined the powder was flour. She says the area will reopen soon.
A guard found the balloon inside the visitors entrance to the Liberty Bell Center, which is in downtown Philadelphia near office buildings, a federal courthouse and Independence Hall.
The Liberty Bell Center building and National Park Service land around it, including Independence Hall, were evacuated, and part of one street was closed to traffic after a guard found the balloon at the visitors entrance around 2:30 p.m.
Testing on the substance was first done at a lab set up at the scene, FBI spokesman J.J. Klaver said. The powder was found to not be explosive or radioactive, but it was what Klaver called a "biological substance."
"We don't know exactly what it is. We know what it isn't," he told reporters at a news conference near the site.
Klaver said one type of biological substance is anthrax, a deadly agent that can come in the form of white powder, but he added other examples are flour and yeast.
The powder was being moved to another laboratory for more testing, which could take up to 24 hours to be completed, he said.
Other nearby buildings, which include offices and a federal courthouse, were not evacuated. Some nearby streets were closed to pedestrians.
Two firefighters and two guards came in contact with the powdery substance but were not contaminated, Klaver said. No injuries were reported.
The Liberty Bell was forged to commemorate the 50-year anniversary of William Penn's 1701 Charter of Privileges, Pennsylvania's original Constitution. The bell, with its famous crack, became an icon of American independence when abolitionists adopted it as a symbol of their efforts to end slavery.
On July 8, 1776, the ringing of the Liberty Bell from the Independence Hall tower called people to the first public reading of the Declaration of Independence.
© Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.