NEW : It 's unclear how Alexis got a shotgun past police . ( CNN ) -- NEW : A Washington police officer ended the 30-minute spree by killing Alexis , mayor said . Alexis had served in the military and with police , but still had some issues . Authorities do n't know his motive , and police say they 're surprised by attack .
NEW : It 's unclear how Alexis got a shotgun past police . NEW : A Washington police officer ended the 30-minute spree by killing Alexis , mayor said . Alexis had served in the military and with police , but still had some issues . Authorities do n't know his motive , and police say they 're surprised by attack .