A gunman opened fire Thursday at the Fort Hood Army base in Texas, killing a dozen people and sending shock waves across the country.

Army officials identified the alleged shooter as Nidal Malik Hasan, 39, a major who was recently promoted from captain and worked at the Darnall Army Medical Center, Ft. Hood's hospital.

The attack began about 1:30 p.m., and ended with 12 people dead and 31 others wounded.

Officials had previously reported that Hasan was among the dead, but he is now confirmed to be hospitalized in stable condition.

Two other soldiers who were taken into custody have been cleared of any involvement and released.

Hasan lived in Silver Spring, Md., and worked at Walter Reed Army Medical Center for six years before being transferred to the Texas base in July.

He held two degrees from the Uniformed Services University of the Health Sciences in Bethesda.

Former neighbors were stunned by the incident, saying Hasan was a quiet man who kept to himself. They say Hasan never displayed any extremist behavior.

The military has not identified a motive in the attack, but federal law enforcement officials say Hasan had come to their attention at least six months ago because of Internet postings that discussed suicide bombings and other threats.

The military has not released the names of those who were wounded or killed.Fort Hood Shooting Rampage