The US flag flies at half-staff as US Senator John Cornyn, R-Texas, delivers remarks on November 6, 2009 outide US Army III Corps Headquarters one day after the shootings at Fort Hood in Texas. US President Barack Obama led his nation in mourning as shocked Americans struggled to understand why a Muslim army doctor unleashed the massacre at a US military base. Getty Images logo Getty Images 2 weeks ago

The US flag flies at half-staff as US Senator John Cornyn, R-Texas, delivers remarks on November 6, 2009 outide US Army III Corps Headquarters one day after the shootings at Fort Hood in Texas. US President Barack Obama led his nation in mourning as shocked Americans struggled to understand why a Muslim army doctor unleashed the massacre at a US military base.