A giant turbine tower at a wind farm toppled, killing a worker atop the structure and injuring another who was inside, a company spokeswoman said.

The workers were doing a routine inspection of the turbine when it collapse on Saturday, said Melanie Forbrick, a spokeswoman for Orlando, Fla.-based Siemens, which manufactures and owns the tower.

Sheriff's Deputy Geremy Shull said the injured worker was in serious condition at a hospital.

The cause of the collapse had not been determined. Officials from the Occupational Safety and Health Administration were investigating on Sunday.

Forbrick said she did not know the height of the turbine. Bonneville Power Administration documents from last year said the turbine towers would stand 263 feet high and reach about 400 feet with blades included.

Portland-based PPM Energy owns the wind farm.

The Klondike III wind project, located in the wheat fields near Wasco, is expected to generate 221 megawatts of electricity when it's completed in late 2007, said Jan Johnson, a spokeswoman for PPM Energy. PPM is using 44 Siemens 2.3 megawatt wind turbines and 80 General Electric 1.5 megawatt wind turbines.