Many Salt Lake County government services are being suspended due to broken air conditioning in its central offices.
Spokeswoman Michelle Schmitt said temperatures in some offices were as high as 100 degrees (37.8 Celsius) Monday because of a heat wave sweeping the region.
Schmitt says the malfunctioning system was caused by a power outage Sunday night and early Monday morning.
Hundreds of employees have been sent home for the day, though some remain at work.
Salt Lake County is Utah's largest county. The central buildings host offices for the county clerk, court and mayor.
Other county services not at central offices remain open, including libraries and health centers.
Facilities staffers are working to repair the cooling system.
Schmitt says county offices will reopen Tuesday.