EL CERRITO, Calif. (AP) — In some ways, California’s Rainbow Day Camp is very conventional, with kids making friendship bracelets, playing basketball and singing songs. But in other ways, it’s extraordinary unique.

The day camp in El Cerrito, in the San Francisco Bay Area, caters to transgender and “gender fluid’ children, ages 4 to 12. Experts say it’s one of the only camps of its kind in the world open to preschoolers.

Rainbow officials say the camp gives kids a safe, fun place to be themselves. The camp’s enrollment has tripled since it opened in 2015, and plans are underway to open a branch next summer in Colorado.

Gender experts say Rainbow’s rapid growth reflects what they’re seeing in gender clinics around the country: an increasing number of kids coming out as transgender at young ages.