Thirteen children suffered acid burns in Reno, Nevada, on September 3 when a “routine” experiment designed to foster understanding of how tornadoes work went awry. Emergency workers responded to a report of an explosion at the Terry Lee Wells Discovery Museum, the Associated Press reports, where they determined that the incident was actually a “chemical flash,” which one spokesman likened to throwing gasoline on a fire.

The experiment, which is designed to create a whirling tornado effect, involves a mixture of methyl alcohol and boric acid, and is conducted at the museum on a daily basis. An officer said that several children sustained acid burns on their hands, arms, and faces. Eight children and one adult were taken to Reno hospital for minor burns and smoke inhalation, according to the AP. The ages of four other people treated at the scene were not released, the report said. All but one of the children were released from the hospital. One child remained overnight for observation.

Amateur video aired on a local television station reportedly showed a flash and flames tumbling off a table onto the floor with several children standing nearby.

The museum posted the following statement on its website regarding the incident:

Reno Fire Department has released an update regarding the investigation into yesterday’s events.  The employee involved in this incident has been placed on administrative leave pending completion of the full investigation. The Discovery continues to cooperate fully with authorities. We would like to thank the community, our staff and volunteers for their support during this difficult time. Our thoughts continue to be with everyone affected. We will continue to provide updates as they become available.