CHICAGO (REUTERS) - US President Barack Obama said on Wednesday he was "heartbroken" that another shooting had occurred at the Fort Hood Army base and described the situation there as fluid.

"We are going to get to the bottom of exactly what happened," Mr Obama told reporters in Chicago, where he is traveling for Democratic fundraisers.

"We're heartbroken that something like this might have happened again."

Mr Obama said his national security team was in close contact with the Defense Department and the FBI to determine what occurred and ensure that everyone was secure.

In 2009 a former Army psychiatrist shot dead 13 people and wounded 32 others in a shooting spree at Fort Hood.

"Any shooting is troubling. Obviously this reopens the pain of what happened at Fort Hood five years ago," Mr Obama told reporters.

"We know these families. We know their incredible service to our country and the sacrifices that they make. Obviously our thoughts and prayers ... are with the entire community," he said.

Mr Obama noted that many of the military members at the base had done multiple tours in Iraq and Afghanistan.

"When they're at their home base, they need to feel safe. We don't yet know what happened tonight, but obviously that sense of safety has been broken once again," he said.