The accident happened on the west side of the building at about 9:20 a.m. Thursday.
Authorities say the victims were knocked off the scaffolding, but luckily they were strapped on. A 23-year-old man suffered cuts to his left arm and right leg, and a 41- year-old man suffered cuts to his face and right arm. Police say their conditions are not known at this time.
Viewer Caitlin McCracken provided video of the rescue she put on Twitter.
The 400 block of Walnut Street, from 4th to 5th streets, is closed.
Both OSHA and L&I have been notified to investigate.