May Day General Strike
California Highway Patrol officers take positions at the Golden Gate Bridge in anticipation of May Day demonstrations in San Francisco, California May 1, 2012. Authorities anticipated demonstrators would shut down the bridge, but agreement was reached to prevent that action. REUTERS/Robert Galbraith
CAIRO - Saudi forces and Yemen's Houthi militia traded heavy artillery fire which blew up part of the main border crossing between the two countries overnight, residents said on Sunday, an escalation of the two-month war.