"We're exploring any potential motive, and domestic terrorism is certainly one among many possibilities," she said.
An improvised explosive device was detonated against the low-slung building, which sits in a mostly residential neighborhood, but a gasoline canister placed next to the device failed to ignite. Members of the FBI's Joint Terrorism Task Force are investigating because of the explosion's proximity to the NAACP office, Sanders said.
Investigators were still looking for a balding white man in his 40s who might be driving a dirty pickup truck. His identity was still under investigation.
"This is someone we'd like to speak to," Sanders said.
