The boy and eight other kids were watching instructors conduct the "sugar snake" combustion experiment, a reaction which happens when baking soda, sugar and alcohol is mixed and lit on fire.
But something went terribly wrong.
"Something happened, there was a fire and the 9-year-old boy got burned," said Napa Parks and Rec spokesperson John Coates.
The injured boy was taken to Queen of the Valley Hospital, then airlifted to UC Davis Medical Center.
The class was taught by the Scientopia Discovery Center. Its director says science experiments have never gone wrong before.
"The kids were standing about 5 feet away from the experiment, the boys shirt caught on fire and staff reacted, made him stop, drop and roll," said Scientopia Director Michelle Dahlberg.
Chemistry camp was canceled Friday, along with future camps this summer through the city of Napa.
"Obviously, this was a tragic accident. We want to understand what caused it to prevent it from happening in the future," said Coates.
he Napa Fire Department is investigating. Officials don't believe there was any criminal wrongdoing but staff will be re-creating the sugar snake experiment to find out what might have happened.
No one else was injured -- parents whose children attend the chemistry camp will be offered full refunds.