The 20th floor of the Collier Center in downtown Phoenix was evacuated after reports of a suspicious substance was found in an envelope.
An envelope containing a suspicious substance was discovered at roughly 11:52 a.m. on the 20th floor of 201 E. Washington. The address comes back to the Collier Center, according to Phoenix Fire.
Two individuals came in contact with the unknown substance in the envelope and were evaluated by Phoenix firefighters.
Police have since determined that the substance is not harmful and allowed people evacuated from the floor to return to work.
Detectives are investigating to determine who sent the envelope.
Editor's note: Phoenix Fire Department previously reported this suspicious substance at Phoenix City Hall. They have since updated the location to the Collier Center.