Tulsa Fire Department Hazmat gave the all clear after responding to a suspicious envelope that was left at the Social Security office on Garnett near the Broken Arrow Expressway.
According to the fire department, the substances that were tested came back as woodchips and petroleum, but nothing hazardous.
The office will remain closed for the rest of the day.
The office was put on lockdown after someone left the envelope in a drop box. Authorities say it contained white powder and also had an oily residue. TFD got the call around 10:40 a.m. Monday.
There were people inside the building when the envelope was found, and they were kept in place to be checked out.