At least five Disneyland employees were hospitalized on Tuesday following a situation involving hazardous materials in a backstage area of the theme park, the Anaheim Fire Department confirmed.

Anaheim Fire Department officials were called to Disneyland at around 12:30 p.m. due to an unknown odor stemming from the “Star Tours” attraction in Tomorrowland.

As of about 1:20 p.m., Anaheim Police Department Sgt. Matt Sutter said four employees who were experiencing dizziness and shortness of breath had been taken to a hospital.

Disneyland officials said materials being used by a contractor produced some kind of reaction backstage at the park. As a precaution, nearby onstage areas were temporarily closed and cleared of guests, but as of 2:10 p.m., Disneyland said those areas were expected to reopen soon.

Park officials said several cast members were treated on site by paramedics and released.

No further details were immediately available.