Three people were injured at a San Francisco performance of the musical Hamilton last night after someone in the audience yelled out the word “Gun!” in the crowded theater.

News reports indicate there was a medical emergency in the audience at the Orpheum Theater that precipitated the incident. However, when someone yelled about the firearm, some audience members thought an active shooter was in the building.

They then panicked, sending other audience members scrambling. The on-stage cast retreated backstage.

Three people sustained non-life-threatening injuries. A woman in the audience had a heart attack and is in critical condition.

“There was no one with a gun, there were no shots fired, at the end it was a medical emergency,” said San Francisco Police Captain Renee Pagano.

Early indications are that a boy in the audience had a seizure when a gunshot sound was enacted in the play, perhaps confusing the audience.

Two people were transported to the hospital with minor injuries to the head and leg.

There was no immediate word on the status of tonight’s scheduled performance of the play.