EAST CHICAGO, Ind. (AP) – The FBI says a pipe bomb caused an explosion that injured an employee at a northwestern Indiana post office.

The agency also said in a statement Thursday that investigators “are still trying to ascertain if there are any terrorism links” to the explosion Wednesday evening at the facility in East Chicago. It says the investigation “remains open and active.”

FBI spokeswoman Christine Bavender says no additional information will be released for now, but that the public is encouraged to contact the FBI with any information. Fire Chief Anthony Serna has said the female postal worker suffered injuries that are not life threatening. East Chicago is about 20 miles (30 kilometers) southeast of Chicago.