Two minors were killed early Friday morning when a limb from an oak tree fell on their tent at Yosemite National Park, park officials said.
The incident took place around 5 a.m. local time at the Upper Pines Campground in Yosemite Valley.
Park spokesman Scott Gediman declined to release the ages or any details about the two to the Associated Press, describing them only as under age 18.
Park rangers responded to campground to provide medical assistance, but both minors were deceased by the time they arrived, officials said.
"Our thoughts are with the families as they grieve this tragedy," park Superintendent Don Neubacher said in a news release.
The names and ages of the victims have not yet been released by park officials while the incident remains under investigation.
Gediman told the AP the campground is one of the parks most popular with a view of Half Dome, and was either near capacity or full when the tree limb fell.
Last month, an 85-foot-tall tree fell in a Pasadena, California park, injuring eight children. The tree had root problems, was leaning and may have absorbed a heavy load of water from a recent storm, according to an arborist's report released Thursday. Some roots were girdled, meaning they were twisted around the main stem of the tree instead of spreading out.
In 2012, a Yosemite concession employee died when his tent cabin was hit by a falling limb.
The Associated Press contributed to this report.