GROVELAND (AP) — A 21-year-old summer camp worker was killed Wednesday when a large oak tree fell at the site near Yosemite National Park, a group said.

The worker was identified as Annais Rittenberg by the Jewish Federation of Silicon Valley, which provides scholarships for children to attend Camp Tawonga. No children were hurt.

Four other adults were treated at hospitals after the tree fell while people were eating breakfast. The tree took down power lines near the campfire but did not damage any buildings.

In an email sent to parents, the federation said some activities were resuming.

"The campers are doing well and are participating in camp activities away from the scene," read the statement attributed to camp director Ken Kramarz. "Our on-site staff therapists are working closely with first responder grief experts to help care for our community in this difficult time."

Rittenberg was a student at the University of California, Santa Cruz, where she was active in the college's radio station, her mother, Penny Kreitzer, told KGO-TV.

Kreitzer said she received a call from the camp earlier today and knew something was wrong.

"I said 'Is she dead?' And he said yes. And then I lost it," she told the station.

Sheriff's officials did not release details about the injuries of the others.

Two women, ages 20 and 21, were treated for minor injuries and released from Sonora Regional Medical Center, spokeswoman Gail Witzelsteiner said.

Memorial Medical Center in Modesto received another of the injured adults by air ambulance, and that patient is in good condition, spokesman Craig Baize said.

Officials at Doctors Medical Center in Modesto said the patient treated there was also in good condition.

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 acres on the Tuolumne River, just outside Yosemite National Park. It has been in operation since 1925, according to its website.