Los Angeles firefighters responded to Brookside Park, just outside the museum grounds in the 400 block of N. Arroyo Boulevard at about 4:45 p.m. Thirty-three kids were participating in a summer day camp at the Kidspace Children's Museum. Several children were outside the camp waiting to be picked up when the tree fell.
Museum staff, firefighters, parents and police quickly converged on the scene.
"I heard a tree crack, and then I turned around and I saw little kids running, then I saw the tree fall on top of the little kids, maybe about five or seven of them. I ran over there with a bunch of parents and we just started going through the tree and the bushes and we started pulling them out," witness Greg Prodigalidad said.
Prodigalidad, who helped rescue some of the children who were trapped underneath the tree, says he couldn't help but think of his own two children.
"My heart was beating thinking about my own kids. I just went out there and I tried to save as many as I could," he said.
Children were loaded onto gurneys and rescuers began cutting the tree limbs apart to see if there were other victims. The children were transported to Los Angeles County-USC Medical Center.
City of Pasadena officials are investigating what may have caused the pine tree to uproot.
"Thank you to the City of Pasadena first responders for their quick action and support, along with our Kidspace community and parents who helped immediately following the incident," the Kidspace Children's Museum said in a statement.
PHOTOS: Kids rescued after tree falls near Kidspace Children's Museum in Pasadena