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.
No children were harmed. They were inside a nearby dining hall having breakfast. The tree took down power lines near the campfire area and dining hall but did not damage any buildings.
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.
PG&E last inspected the area where the tree fell in December 2012, spokesman Brian Swanson said. During such inspections, the utility looks for tree limbs growing close to power lines and obvious signs of decay or defects in trees around them.
Swanson said PG&E was still inspecting the tree that fell.
Rittenberg was an environmental studies major at the University of California, Santa Cruz, where she was a popular college DJ who served as world music director at the school's radio station, station manager Alec Howard said. The camp's executive director, Ken Kramarz, called Rittenberg a "beloved member of our staff."
"As our own hearts are still hurting, we send our sincerest condolences to her family and loved ones," Kramarz said in an email sent to campers' parents.
Rittenberg's mother, Penny Kreitzer, heard about the tree through the news before she knew her daughter was involved. Kreitzer frantically called hospitals and was briefly hopeful when she couldn't find Rittenberg before learning the truth through a law enforcement official.
"I've lost a beautiful child through that tree," Kreitzer, told the Los Angeles Times. "I wish the tree had fallen on Saturday when no one was there."
There were about 300 campers and 150 staff at Camp Tawonga, which offers sessions for students in second through 12th grades. The camp is located on 160 lush acres on the Tuolumne River, just outside Yosemite National Park. It has been in operation since 1925, according to its website.
Kramarz said the children had been told only that a tree fell and some staff had been injured.