The Social Security Administration building in Casa Grande, Ariz., was evacuated Friday morning after an explosion, authorities said.
A small, simple device exploded and charred the outside of the building’s side doors about 8:25 a.m., said Case Grande Fire Marshal Barbara Rice. A car near the entrance appeared to be damaged.
“It wasn’t a pipe bomb or anything of that nature,” she said.
There was smoke damage inside the building and briefly a fire, but no one was injured, Rice said.
The FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives is investigating.
Authorities said they had identified a person of interest related to the bombing and could make an arrest later Friday.