A three-alarm fire burned late on Tuesday night at the headquarters of Apple Inc.

The fire occurred at a building situated on the company's main campus in Cupertino, CA at approximately 10pm local time and burned for approximately three hours.

Local reports indicate that no injuries were reported and that all employees in the building were safely evacuated.

According to local television station KNTV, the blaze reportedly started beneath an air conditioning duct in a building known as Valley Green Number Six, a facility that was reportedly housing research and development projects for the company.

The station reports that maintenance crews had been working on the air conditioning systems in the building earlier in the day.

No damage to any other buildings was reported.

Apple first opened its Cupertino headquarters in 1993, choosing '1 Infinite Loop' as the official address. The complex consists of six buildings and houses all the company's major corporate entities.

The company also has campuses in Austin, TX. Cork, Ireland and Singapore.