13 injured at Nevada museum when experiment goes wrong

(CNN) -- Thirteen people, including children, were injured Wednesday when an experiment went awry at the Terry Lee Wells Nevada Discovery Museum in Reno, police said.

"Of the 13 injured, four were treated and released and nine were transported to a local hospital," Reno Officer Tim Broadway said.

"There were seven children and two adults taken to the hospital with chemical burns to their arms, hands and face. None of the injuries are life-threatening, but we do not know their exact condition," he said.

Broadway said they were hurt in an explosion caused by a tornado experiment, in which chemicals were mixed incorrectly. The Reno fire chief has called what happened a chemical flash, the officer said.

The museum tweeted that preliminary reports of an explosion were inaccurate.

"A routine science demonstration didn't happen as usual causing a flash," it posted. "The Discovery is focused on the safety of its visitors at this time. More information coming soon."

CNN's Tony Marco contributed to this report.