Officials said a white powder found this morning in the mailroom of the Wells Fargo bank building at 4th and Market Streets is inert.
But the investigation forced the closure of 4th Street between, Market and Arch Streets, for 90 minutes as fire officials combed through the basement and parking garage at the building.
Asa Grimes, chief of the Fire Department's Battalion 4, said events began early this morning, shortly before 5 a.m., when four workers in the mailroom noticed a white, powdery substance spilling from a mailbag.
The alerted security, which called police and the hazardous materials unit. The power was isolated and tested. The scene was declared safe and cleared about 6:30 a.m.