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. “I was probably 4 feet away from him. I said, ‘Do you realize how dangerous this is? There’s a raging forest fire up the trail. This place is so dry.’”

But her reference to an existing wildfire that had forced the closure of the trail miles ahead and her warnings about reckless behavior drew no response, she said.

“They kept on walking down the trail,” FitzGerald said.

Oregon State Police said a 15-year-old boy from Vancouver is suspected of starting the fire. They have made no arrests and are not releasing the boy’s name. They are asking witnesses who were on the trail Saturday between 10 a.m. and 5 p.m. to call them at 503-375-3555.