Wednesday's mass shooting at Fort Hood, in which Spc. Ivan Lopez killed three soldiers and wounded 16 more before turning the gun on himself, may have been caused by an argument over leave forms.

New York Times article quotes an anonymous "law enforcement official" who said Lopez requested leave for "family matters," and was angry when the request was denied. The father of a solider wounded in the attack told WLBT that Lopez came to a personnel office to get a leave form, but was told to come back the next day. Instead, Lopez came back with a gun and opened fire.

Lopez's own family believes he was distraught over the recent deaths of his grandfather and mother, while a friend said Lopez was angry that he was only given a 24 hour leave to attend his mother's funeral.

Lopez was being treated for mental health issues including anxiety and depression, but Lt. Gen. Mark A. Milley said Friday that investigators do not believe they were a direct cause of the attack. 

"We believe that the immediate precipitating factor was more likely an escalating argument in his unit area," Milley said. 

Sgt. Danny Ferguson, 39, Sgt. Carlos A. Lazaney-Rodriguez, 38, and Sgt. Timothy Owens, 37, were killed by Lopez. Two of them were in his unit.

Meanwhile, some of the victims from Ft. Hood's other infamous mass shooting told the Los Angeles Times that they've been let down by the government in the years since. The shooting was not classified as a terrorist act, so victims' deaths and injuries were not considered combat-related. That means they are not entitled to certain benefits. Some have struggled to pay their considerable medical bills. In 2011, 148 victims and family members sued the government for compensation.

Both Lopez and Maj. Nidal Malik Hasan, who killed 13 people in 2009, purchased the weapons they used in their shooting rampages at Killeen's Guns Galore