PORTLAND — A woman who was hiking over the weekend in the Columbia River Gorge said Tuesday that she happened across a teenager who threw “a smoke bomb” into Eagle Creek Canyon, igniting the now 10,000-acre Eagle Creek fire. Liz FitzGerald, 48, of Portland said she’s fairly certain that she heard the teenager’s friends — including a boy who was video-recording with his cellphone and some girls in the group — giggle as the firework dropped down a cliff and into the trees below. “I saw this shorter kid lob this smoke bomb down into the canyon,” FitzGerald said.