PHOENIX - The U.S. Postal Service confirmed the two suspicious letters found Wednesday morning at U.S. Sen. Jeff Flake's office in Phoenix were not a threat after all.
USPS spokesman Keith Moore confirmed they launched an investigation into the discovery around 9 a.m.
It all started when Phoenix police received a call regarding the letters found at the office building near 22nd Street and Camelback Road.
The letters were stained with an oily substance and did not have a return address.
Phoenix police Sgt. Tommy Thompson said precautions were taken due to events around the nation over the past two days.
Members of Flake's staff told ABC15's Kimberly Cheng they were asked to leave the building but were not evacuated.
Phoenix fire Capt. Jonathan Jacobs said the suite where the items were found was evacuated and the ventilation system shut down.
He said staff reported it was some type of powder substance, but they did not open the envelopes.
Thompson said the two workers and the police officer were taken to the hospital for precautionary evaluations and later released. One of the workers was treated for a medical condition unrelated to the threat.
Thompson said that besides Phoenix police and firefighters, the FBI, Bureau of Alcohol, Tobacco, Firearms and Explosives and a U.S. Postal Inspector were at the scene.
ABC15 video from the area showed crews donning protective suits before entering the building.
Sen. Flake thanked responders in a tweet Wednesday afternoon, "Suspicious pkg at my Phx office cleared, no dangerous material. Thx to Phx PD + FD, FBI, ATF + USPS for quick response. Everyone safe."
Sen. Flake's press secretary, Genevieve Rozansky, sent this email to ABC15: "There was a suspicious letter intercepted by a member of Senator Flake's staff at his Phoenix office. At this time, we do not yet know any more details as to the contents of the letter. Law enforcement officials are on the scene, and all staff members are safe. We will release details as we know more."
This comes on the same day that a suspicious envelope was found addressed to President Obama .