The dead gunman, army major Hassan Malik, was believed to be a recent convert to Islam and was soon to be deployed to Iraq.
The army major is believed to have been a doctor on the military base who specialised in mental health.
Military officials held two other soldiers in custody on the Soldier Readiness Centre at Fort Hood, the world's largest base, but it is not clear at this stage if they were connected with the violence.
It is believed that shooting may have started during a graduation ceremony attended by large numbers of young military personnel, and could have been the work of a lone gunman.
Soon after the shooting rampage, which occurred at 1.30pm Texas time, about 500 military personnel performed a security sweep of the base to prevent any further violence and to check for further suspects.
Some of those killed are believed to have been shot at point-blank range with handguns, with the shooter or shooters reloading multiple times.
US President Barack Obama described the shootings as tragic and sent his condolences to the families of those murdered.
"This is a horrific outburst of violence," he said.
The President broke from a prepared speech to the Tribal Nations Conference in Washington to say there had been a tragic shooting in Texas but details were unclear.
"What we do know is that a number of American soldiers have been killed and even more have been wounded in a horrific outburst of violence," he said.
"My immediate thoughts and prayers are with the wounded, and with the families of the fallen, and with those live and serve at Fort Hood.
"Theses are men and women who have made the selfless and courageous decision to risk, and at times give, their lives to protect the rest of us on a daily basis.
"It is difficult enough when we lose these brave Americans in battles overseas. It is horrifying that they should come under fire at an army base on American soil.
The President said he had spoken to Defence Secretary Robert Gates and Chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, and he would receive a constant stream of updates.
"We are working with the Pentagon, the FBI and the Department of Homeland Security, all to ensure that Fort Hood is secure and we will continue to support the community with the full resources of the federal government.
"In the meantime I would ask all Americans to keep the men and women of Fort Hood in your thoughts and prayers.
"We will make sure that we get answers to every single question about this horrible incident and I want all of you to know that as commander in chief there is no greater honour, but also no greater responsibility for me than to make sure that extraordinary men and women in uniform are properly cared for and that their safety and security when they are at home is provided for."
Congress today held a moment of silence to honour the dead victims in the Fort Hood shootings.
Source: The Australian