CHICAGO (CBS)– The Daily Herald’s office building was evacuated due to a suspicious package Thursday, but reopened about an hour later.

According to an article posted by the Daily Herald, the package was discovered at the reception area of the office building in Arlighton Heights.

It was described as a 9-by-12-inch envelope, with an angry political message written on it. A white powder fell out of the envelope as it was being handled, and employees called 911.

According to the Daily Herald, three employees were examined for exposure to the substance, but showed no symptoms.

Employees were allowed back into the building after about an hour, but the first floor offices remained off limits while firefighters tested the area for potential hazards. Fire officials told the Daily Herald they were able to rule out any danger to the rest of the building.