In the latest eruption of mass violence in the United States, a dozen people were shot dead and at least 14 others injured Monday morning when a gunman opened fire on military and civilian employees at the Washington Navy Yard, located in southeast Washington DC, just a few miles from the White House and capitol building.

Police killed the alleged gunman—identified as a military contractor—in a shootout, bringing the total number of fatalities to 13. This is the largest loss of life in a single incident in the American capital in over 30 years.

The attack occurred at a building housing the Naval Sea Systems Command for the US Navy, which is responsible for building, buying and maintaining naval ships and equipment. There are 3,000 employees at the location, which was locked down while police SWAT teams and other uniformed personnel swept the building.

There were initial reports of multiple gunmen throughout the day, but by the evening officials said it was likely the act of a lone perpetrator. Late into the day, however, DC police said there was one other possible suspect, described as wearing a military-style uniform.

Police identified the dead suspect as 34-year-old Aaron Alexis, a civilian information technology contractor for the Navy from Fort Worth, Texas. According to reports, Alexis had served for four years—from 2007 to 2011—in the Navy Reserve until being discharged for “a pattern of misbehavior,” which officials refused to detail. 

Alexis reached the rank of Aviation Electrician’s Mate 3rd Class and was decorated with the National Defense Service Medal and the Global War on Terrorism Service Medal, a Navy official told Reuters. Family members reported that he had been sent overseas while in the armed services. 

Officials said it was unclear whether Alexis was working at the Washington Navy Yard in a civilian capacity at the time of the incident. They also said it was not known how the alleged gunman brought weapons into the building. While military personnel are generally banned from carrying weapons on military installations, it has been reported those with credentials are not routinely checked.

According to several media accounts, Alexis had earlier encounters with police. The most recent was in 2010, when Fort Worth police arrested him for discharging a firearm within city limits. Misdemeanor charges were dropped after investigators accepted his story that the weapon had gone off accidentally while Alexis was cleaning it.

Reuters reported that Alexis had also been arrested in Seattle in 2004 for shooting out a construction worker’s car tires in an anger-fueled “blackout” triggered by perceived “disrespect,” according to the Seattle Police Department. Alexis told detectives “he was present during the tragic events of September 11th, 2001, and how those events had disturbed him,” according to a police report.

Employees at the Navy Yard were given orders to “shelter in place,” as authorities also shut down streets and bridges in the vicinity. Admiral Jonathan W. Greenert, chief of naval operations and a member of the Joint Chiefs of Staff was reportedly evacuated along with his family from his residence on base upon the initial shots being fired. 

The shooting rampage sent shockwaves throughout Washington DC. Federal buildings in the Washington area were immediately placed on alert, with increased police presence at all locations. Flights were briefly halted at Reagan National Airport, and as many as ten DC public and charter schools were placed on lockdown. An announcement by the Senate Sergeant-at-Arms informed employees at the US Capitol building that “out of an abundance of caution,” the legislative headquarters of Congress would be shut down, with no one allowed to enter or leave the premises.

This was the worst attack at a US military installation since US Army Major Nidal Hasan opened fire killing 13 soldiers and wounding 31 others at Fort Hood, Texas, in 2009.  Hasan said he acted in retaliation for US wars in Muslim countries. In August, he was convicted and sentenced to death by a military jury.

Speaking of the regularity of mass killings in America, Janis Orlowski, the chief medical officer at MedStar Washington Hospital Center, where several of the victims from the Navy Yard were admitted, commented, “There’s something evil in our society … when we have these multiple shootings, these multiple injuries. I would like you to put my trauma center out of business,” she added.

After decades of mass shootings—from Columbine to Newtown, Connecticut—President Obama responded yesterday with routine platitudes. “We are confronting yet another mass shooting, and today it happened at another military installation, in our nation’s capital,” said President Barack Obama in a brief statement.

The president proclaimed the victims of the shooting to be “patriots” who “know the dangers of serving abroad” and faced “unimaginable violence they wouldn’t have expected at home.”

In fact, the endless military violence perpetrated by Obama and his predecessors is having its inevitable repercussions in America, as hundreds of thousands of soldiers return home after being physically and psychologically damaged from the wars carried out by the US government.

A recent study released by the American Medical Association (AMA) showed that since 2005, suicides within the US military have skyrocketed. The report tracks the increase of such fatalities as being up from 10.3 to 11.3 per 100,000 in the base year to being over 16.3 per 100,000 just three years later. The increased rate of depression, suicide, and other forms of mental breakdown has been directly attributed to increased deployments for troops into combat zones.