Czech TV journalist Bohumil Vostal was capturing what he thought would be a majestic shot — San Francisco’s iconic City Lights bookstore, steeped in the gathering dusk — when three masked assailants approached with guns pointed. “They were heading at my camera man, aiming a gun at his stomach, and one at my head,” Vostal said in an interview Monday, growing breathless as he recounted the harrowing incident at 5 p.m. the night before. Vostal is among hundreds of international correspondents who flocked to San Francisco this week for the Asia-Pacific Economic Cooperation summit, an event drawing some of the...