FREEHOLD - Several teenagers were taken to a hospital after an incident during a concert at iPlay America in Freehold.

It happened Saturday night, when a large group apparently crowded the stage during the Dolan Twins performance.

The Monmouth County Sheriff's office reports that seven people were taken to a hospital complaining of hyperventilation and heat exhaustion.

Authorities say several other teens were treated at the scene.

Ethan and Grayson Dolan, 16, are best known for posting videos on YouTube and the smartphone app Vine. They are originally from New Jersey.