Authorities have closed a wide swath of popular campgrounds and backpacking areas along the Pacific Crest Trail in Washington as they search for a former Army soldier wanted in the deaths of his three young daughters.

Travis Decker is a former member of the military who has enough wilderness survival skills to live in the woods on his own for weeks or months, the authorities said.

More than 100 officers and agents and helicopters have joined the intensified search for Travis Decker, suspected of killing his three daughters in Washington state.