The park where this happened is about 17 miles from Palo Alto, but paramedics were on the scene in less than 15 minutes because there was a fire station just down the road.
At 5 a.m. several campers say they heard a loud crack followed by screams coming from campsite D1. An oak tree fell on top of the boy's tent at Memorial Park in San Mateo County and two 12-year-old boys were sleeping inside.
"It was a tan oak tree, probably about 15 to 20 inches in diameter and about 50 to 60 feet tall," said Dave Holland, the San Mateo Assistant County manager.
Holland says the tree fell short of completely crushing them, but the impact of the trunk as it flexed across one boy's pelvis was enough to cause critical injuries. The other boy escaped with cuts and bruises.
"As far as I know there were no wind conditions that contributed to this," said Holland.
The boys were part of a week-long family gathering that returns to the camp site each year. Some members are from California and some from Arizona.
"Total surprise. I have not heard of such a thing," said Lomar resident Dorothy Myers.
Myers lives in the area and says the park does a good job of grooming the camp sites.
San Mateo County says it has a program that checks for rotten trees at camp sites every spring just before the camping season begins. Investigators say the fallen tree has obvious signs of brown cubicle rot, which is common in oaks, but they're not sure of the tree's health when it was examined this past spring.
"It's a whole procedure on looking at the condition of the tree and the shape it's in and which way it leans and those kinds of things. If we give it a hazardous tree rating we remove the tree," said Holland.
Holland says a further investigation of the records will explain why that tree passed the examination this past spring.
