US investigators believe gunman acted alone in rampage

US investigators believe the army doctor accused of killing 13 people in a shooting rampage at a Texas military base acted alone, but his motive for the massacre was unclear.

President Barack Obama will Tuesday attend a memorial service to honor victims of the rampage at Fort Hood attributed to Muslim US army doctor Major Nidal Malik Hasan, who is also suspected of wounding 30 people. “All evidence at this point indicates the suspect allegedly acted alone,” Chris Grey, spokesman for the US Army criminal investigation division (CID), told reporters, adding that no motive had yet been established.