2 people critically injured in a mine shaft explosion in Placer County, California on Friday.

2 people critically injured in a mine shaft explosion in Placer County, California on Friday morning. The explosion happened around 9:40 a.m. at a mine along Mosquito Ridge Road within Tahoe National Forest, according to the Foresthill Fire Protection District. Both injured individuals were airlifted to Sutter Roseville Trauma Center for treatment. The cause of the explosion is under investigation by the Bureau of Mine Safety.