2 incredibly seriously injured in Northern California mine explosion in PLACER COUNTY - Two people were seriously injured in an explosion at a Northern California mine, officials said Friday. The Foresthill Fire Protection District said it happened just after 9:41 a.m. in a crash on Mosquito Ridge Road at Gorman Ranch Road in Placer County. Employees in the Foresthill District and the US Army. The Forest Service found the couple after the explosion. They were then airlifted to Sutter Roseville Trauma Center, where they were treated.