(CASA GRANDE, Ariz.) — Federal authorities are investigating the cause of a small explosion behind a Social Security Administration office in Casa Grande, Ariz., on Friday morning.
The explosion occurred outside a heavy metal security door at the side or rear of the office, a Casa Grande fire official tells ABC News.
There were no injuries.
The building sustained minimal damage. A small fire ensued but was quickly extinguished.
The device is described as a “non-complex” device and is not a pipe bomb, the official said.
Local officials and representatives from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were on the scene. The office is located about 50 miles south of Phoenix.
The Arizona Republic reports the investigation has been handed over to the FBI.
Copyright 2012 ABC News Radio
Chuck Johnston, CNN Newswire