A small group of people gathered at Freedom Plaza in Washington D.C. to mourn the victims of the Navy Yard shooting.

Twelve people plus the suspected gunman were killed during Monday's bloody spree.

Eight more were injured, three of them suffered gunshot wounds.

The FBI identified the suspect as Navy contractor Aaron Alexis.

Washington Metropolitan Police Chief Cathy Lanier says they're now convinced no second suspect was involved and the gunman acted alone.

(SOUNDBITE)(English) WASHINGTON D.C. METROPOLITAN POLICE DEPARTMENT CHIEF OF POLICE, CATHY LANIER, SAYING:

"We feel comfortable right now that we've exhausted all means to eliminate that possible last suspect so we do now feel that comfortable that we have the single and sole person responsible for the loss of life inside the base today."

The FBI said Aaron Alexis was a Navy contractor with valid access to the base although he'd had two gun-related brushes with the law.

A Navy officia