Special Agent Jessi Rice said Tuesday that the blast in the Tulsa suburb of Bixby is not being called terrorism because investigators have not determined a motive and have not identified a suspect.
From outside the tape, it is apparent that the office's front doors were damaged by the explosion.
Bixby and Tulsa Police received several reports of the explosion just after 10:30 p.m. Bixby requested Tulsa Police bomb squad because of a possible pipe bomb. Officials from the FBI and ATF, the federal agency in charge of investigating bombs, are also present should the explosion fall under their jurisdiction - for example if it is classified an act of domestic terrorism. Rice added the exact type of bomb used in the attack on the military facility can not yet be confirmed.
"At this point we don't know if it was a disgruntled employee, an act of domestic terrorism, just someone playing games", Rice said.
A witness reported that someone on a motorcycle was in the area, and agents are pursuing that lead as they conduct interviews, Rice said.
A business owner whose store is close to an Oklahoma Air Force recruiting station that was damaged in a late-night explosion says he suspects it was an attack fueled by anger.
Police said the center was closed at the time of the bombing and that no one was injured. That vandalism included slashed tires.
It is noted that Federal Bureau of Investigation and ATF are investigating the cause of the explosion.