Several people were injured, including seven children, in an explosion at the Nevada Discovery Museum in Reno where docents were demonstrating how to make a smoke tornado.
Authorities say that about a dozen children were seated six to 10 feet away from the routine experiment. They add, that the order in which the chemicals were applied got switched, causing a flash that lasted two to four seconds.
One child suffered second-degree burns and was kept overnight at Renown Regional Medical Center for observation. Officials with the hospital say six children and two adults were also treated, but released.
No serious damage was reported to the building. Reno Fire says it plans to recommend that the museum review its safety procedures.
The tornado effect is created when a cotton ball soaked with methyl alcohol is dusted with boric acid and then set on fire inside a large glass container. The jar is set on a Lazy Susan, then spun around to create a miniature green whirlwind.