D.C. police: 'Comfortable' single gunman involved in shooting

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“We do now feel comfortable that we have the single and sole person responsible for the loss of life inside of the base today,” Lanier said. She said police will update the public if that changes. 

Earlier in the day, reports varied about how many shooters were involved with the killings, with Lanier telling reporters at one point that there were two possible other shooting suspects.

One person of interest was cleared early Monday afternoon. The second individual still has not been found, but Metro police determined that it had exhausted all means in ruling him in or out. 

He had been described as a black male 40-50 years old with graying sideburns and wearing an olive military uniform.

Washington Mayor Vincent Gray said that there is no evidence to conclude that there were multiple gunmen, but authorities are still not ruling it out. 

Alexis, who had served in the Navy from 2007-2011, had legitimate access to the Navy Sea Systems Command in Navy Yard where the shooting took place, said Val Parlave, the FBI field district’s assistant director.

Thirteen people, including Alexis, were killed Monday morning. Eight people were injured, including three who sustained gunshot wounds, according to Gray. 

All the victims are between 46-73 years old. At this point, no military personnel had been identified as victims.