Updated

A U.S. Army report says Fort Hood did not have a system in place that could have anticipated a deadly rampage last April that left four soldiers dead and 16 wounded.

The report released Friday says there were no clear warnings that Spc. Ivan Lopez would go on a two-block shooting spree before killing himself. It concluded Lopez's supervisors would have had difficulty recognizing any personal problems leading up to the attack.

The report found that no single factor prompted the incident, despite Army investigators' previous findings that Lopez was in an argument over a leave request before the shooting.

Investigators have said the 34-year-old Iraq War veteran was undergoing treatment for depression and anxiety while being evaluated for post-traumatic stress disorder but was not considered "likely" to commit violence.