Emergency crews are responding to a "mass casualty incident" in Tuolumne County after a tree fell at a Jewish camp for kids.
Hospital officials in Sonora confirmed that at least one person was killed and four people were airlifted from the scene.
Cal Fire public information officer Daniel Berlant tweeted that the incident occurred at Camp Tawonga in Groveland and that 20 people were reported injured.
Gregg Rubenstein, director of finance at Camp Tawonga, said staffers were still assessing the situation.
They said some adult staff members were injured, but no children.
The website mymotherlode.com reported that a tree had fallen through a dining hall.
Tuolumne County Sheriff's Office Spokesman Sgt. Jim Oliver told the website that officials were working to rescue some children trapped underneath the tree.
Sheriff's officials told The Times they were still in the process of determining the extent of injuries.
Camp Tawonga is a 160-acre Jewish youth camp set in the middle fork of the Tuolumne River in the Stanislaus National Forest outside of Yosemite National Park. There are about 160 employees who work in the camp’s summer program, according to the camp’s website.