A portion of Broadway near the popular shopping plaza was blocked for several hours as investigators combed the scene.
Police say that the three workers fell approximately 20 feet. Authorities say the men were working on an external planter box when the scissor-lift became unstable. The cause for the fall is under investigation.
Glendale Fire Department Capt. Vince Rifino said that all of the three men landed in the middle of Broadway and suffered "significant medical problems." They were transported to the USC Medical Center.
Rifino pointed out that the fall victims were not city workers. They were workers employed by the Galleria.
Officials say that the Occupational Safety and Health Administration is investigating the accident.
"The maximum identified on the scissor-lift says two people at a 500-pound maximum capacity and there were three gentlemen working up there," said Rifino. "Also, they had a trash can that had some debris, some rock and sand inside up there with them on top of the platform."
All three workers received serious injuries and at least one is in critical condition.