alarms on the base went off immediately and people were told to shelter in place. >> shelter immediately. >> ft. hood is no longer on lockdown. officials say the fbi is on the scene and there's no indication that this incident is tied to any form of terrorism. according to nbc news pentagon correspondent jim miklaszewski. officials believe it began as an argument that erupted into gunfire. pete williams reports that there is still an ongoing search for a possible second gunman, but officials increasingly believe there was only one shooter. both president obama and defense secretary hagel have been briefed. the president made a statement in chicago earlier. >> i want to just assure all of us that we are going to get to the bottom of exactly what happened.