WEED, Calif. — When fire crews in the Shasta-Trinity National Forest responded to multiple lightning-caused fires in the wake of last week's thunderstorms, they attacked them aggressively and eventually left the scene believing that they had been contained, according to an official. But one of those starts came burning back to life, soon spreading beyond what the local crews could control. As of Wednesday morning, the Lava Fire covered almost 17,600 acres, stretching from the slopes of Mount Shasta to the outskirts of Weed, and north across Highway 97 into the Juniper Valley area. While fire officials have yet to confirm how many buildings have been destroyed, the Siskiyou County Sheriff's Office heavily implied that at least some areas have burned.