Police and the FBI responded to three anthrax scares around Oklahoma City Thursday afternoon.
The first happened at 2 p.m. when the first letter arrived at the U.S. Attorney's office downtown. The letter had a white powdery substance in it.
A second letter arrived at the Federal Courthouse a few blocks away nearly two hours later.
Then the final envelope arrived at FBI headquarters in Northwest Oklahoma City at 5:30 p.m.
An FBI spokesman tells News 9 all three letters were sent by an inmate at McAlester Correctional facility. The letters have been sent to a lab to be tested.