Police rule out second shooter in Washington massacre

Washington, Sep 17 (EFE).- Investigators have ruled out the involvement of a second individual in the shooting rampage that left 13 people, including the gunman, dead at the Naval Sea Systems Command Headquarters in Washington, District of Columbia Metropolitan Police chief Cathy Lanier said.

Aaron Alexis, a former Navy reservist who had a valid pass to enter the facility, likely acted alone, Lanier said.

"We do now feel comfortable that we have the single and sole person responsible for the loss of life inside the base," the police chief said.

The incident on Monday was the worst shooting at a military base since 2009, when an Army psychiatrist killed 13 people at Fort Hood in Texas.

Police initially said they were looking for a second shooter based on statements from eyewitnesses and security camera footage.

The 34-year-old Alexis's military record indicates that he was a Navy reservist from May 2007 to January 2011, when he was hired as a contractor, the Pentagon said.

The Sea Systems Command HQ is located inside the Washington Navy Yard, in the eastern part of Washington D.C.

Around 3,000 people work in the building.

President Barack Obama received several briefings on the shooting from Assistant to the President for Homeland Security and Counterterrorism Lisa Monaco and Deputy Chief of Staff Alyssa Mastromanaco, the White House said.