LOS ANGELES (CNS) — A package containing "concerning content" prompted a hazardous materials investigation Thursday in a Los Angeles City Hall East mail room, and two people were taken to a hospital as a precaution for evaluation.

Police and fire fighters responded to the mail room in the building at 200 N. Main St. shortly after 2:40 p.m., according to Los Angeles Fire Department spokeswoman Margaret Stewart. She initially said a white powdery substance had been discovered, prompting the response.

Stewart later said two workers in the mail room had opened a package "with concerning content" inside, but "no substance was visible in the package."

The workers were evaluated by paramedics at the scene, then taken to a hospital as a precaution, though neither was showing any symptoms of illness.

Stewart said the mail room and several adjacent businesses were evacuated as a Los Angeles Police Department bomb squad responded to the area to check other packages in the room.

Stewart insisted there was no active threat to City Hall, City Hall East or public safety.

Investigators concluded their investigation around 6:10 p.m. and determined that no hazardous substance was within the mail room or other nearby offices.

They have cleared the scene for businesses to resume regular operations.

As the investigation continued, Los Angeles Street was closed between Temple and First streets.