OKLAHOMA CITY (AP) - Dozens of construction workers and state employees were ordered from the state Capitol after building officials say an alarm was triggered while air filters were being changed.

Office of Management and Enterprise Services spokesman John Estus said Friday that changing the filters stirred up dust that triggered the alarm. He says it was not related to ongoing construction of House offices on the first floor.

Oklahoma Highway Patrol troopers who provide security at the building went from office to office, ordering workers out of the building. Most gathered in the shade for about 30 minutes before they were allowed to re-enter the building.

The Capitol has been evacuated several times in recent months after construction workers triggered the building's alarm.