Firefighters said no one was hurt and that they did not know when the street would re-open.
Just before noon, sheets of ice periodically crashed onto the sidewalk, sending chunks flying into the roadway.
Firefighters said someone from the offices across Tejon Street called to report ice.
The building was designed by the Boulder office of the national firm Oz Architects.
The project’s lead architect, Kelly Davis, could not be reached for comment.