The FBI has taken a leading role in investigating an explosion at a post office in Eastern Chicago, Indiana that injured a postal worker.
Authorities said an explosive device was detonated at the post office in northwestern Indiana at about 6 p.m. Wednesday.
Injured in the explosion was a female postal worker. Her injuries don’t appear to be life-threatening.
The Chicago Tribune reports  that two employees were inside the post office during the explosion.
East Chicago Fire Chief Anthony Serna said it wasn’t immediately clear whether additional bombs were found.
Whatever the case, Serna said, bombings like this are rare.
“Bomb threats, yes,” Serna said. “An actual explosion like this is rare.”
The FBI is taking over the case because the explosion occurred in a federal building.
No suspects were in custody as of Thursday morning.