The FBI is trying to determine “if there are any terrorism links” to the bomb that exploded at an East Chicago, Ind., post office on Wednesday, but insisted “there is no ongoing public safety concern.”
The Chicago Tribune confirmed  from the FBI that a pipe bomb caused the explosion shortly after 6:30 p.m.
“At this time, investigators are still trying to ascertain if there are any terrorism links,” FBI spokeswoman Chris Bavender said in a release.
The explosion injured a female post office employee, who sustained non life-threatening injuries.
The post office was “up and running for business” Thursday morning, U.S. Postal Inspector Mary T. Johnson said.
“There is no disruption of mail delivery service,” Johnson said.
The post office was not damaged in the explosion.