Shooting at Navy's largest system command

The Sept. 16 shooting that rocked the Navy Yard in Washington happened at the headquarters of the largest of the Navy's five system commands.

The Naval Sea Systems Command is housed in the Navy Yard's building 197, which was the scene of the shooting that early reports said left four dead and at least eight injured. Roughly 3,000 people work in the building, including civilian, military and contract support personnel. NAVSEA counts 60,000 personnel among its ranks, according to the command's website.

NAVSEA's annual budget is about $30 billion, a quarter of overall Navy spending. The command oversees the engineering, construction and maintenance of the Navy's ships, submarines and combat systems, which includes a significant portion of shipboard naval IT systems. NAVSEA also handles all related acquisition and business management, including 150 acquisition programs.

The command is responsible for the technical authority, development, acquisition and support of Navy ships and integrated warfare systems, as well as for technical standards in Navy systems. It plays a key role in Navy enterprise activities and systems, including several subordinate program executive offices. Among those are the PEOs for Ships, Integrated Warfare Systems, Littoral Combat Ships, Aircraft Carriers and Submarines. It also oversees the Naval Surface Warfare Center, the Naval Undersea Warfare Center and the Naval Regional Maintenance Center, among other offices.

NAVSEA is headed up by Vice Adm. William Hilarides, who only recently took over as commander on June 7. Prior to that, Hilarides served at sea as well as on the staff of several Defense Department organizations, including within the U.S. Atlantic Fleet, the Joint Staff and the Chief of Naval Operations.

It was unclear if Hilarides was in the office at the time of the shooting, and no victims' names have been reported.

In the hours after the shooting, the NAVSEA Twitter account posted thanks for public concern and asked for continued support.

"Thank you for thoughts and prayers. Many of us evacuated and safe. Please pray for safe evacuation for anyone still in building," the NAVSEA tweet stated.

Navy Secretary Ray Mabus also took to social media to voice support for NAVSEA.

"I'm deeply shocked & saddened by the shooting this morning at the Navy Yard. Our thoughts [and] prayers are with the victims and their families," Mabus tweeted.