An explosion erupted on Friday morning at a federal office building in Casa Grande, Ariz.

The explosion occurred around 8:15 a.m. local time at a Social Security Administration building. Although there were multiple people in the building at the time, there were no reported injuries. Authorities said the explosion appeared to be triggered by a device, which was placed on the back door of the building.

AzFamily.com reported that U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives was sending investigators to the site of the explosion.