SAN FRANCISCO - Staff members at a summer camp near Yosemite National Park were having breakfast outdoors when they felt what the parent of one counselor described as an earthquake.

About 40 feet of a large, 53-inch diameter black-oak tree snapped off and came crashing down, killing a 21-year-old art counselor and injuring four others.

Jennifer Rosenberg told the Los Angeles Times her daughter described Wednesday morning's tree fall as an earthquake "and then a big dust cloud."

Authorities don't know whether the counselor who died, Annais Rittenberg, was seated in the area where the tree fell, but other Camp Tawonga staff members were having their breakfast there, Tuolumne County Sheriff's spokesman Sgt. James Oliver said on Thursday

Oliver said the tree snapped about 32 feet from the ground.

Two of the injured adults were treated and released. The other two, Lizzie Moore and Cara Sheedy, were in good condition at hospitals in Modesto, nursing supervisors said on Thursday.

Oliver said sheriff's officials don't plan any further investigation into what caused the tree to fall. Because of the nearby power lines, authorities said Pacific Gas & Electric Co. was responsible for annual inspections of the oak tree.

PG&E officials who looked at the tree's stump on Wednesday said the tree showed no obvious signs of rotting or disease, Oliver said. Weather also did not appear to be a factor.