LINCOLN, Neb. (AP) — An enclosed tennis court at a sports complex in Lincoln has collapsed, though authorities say there are no reported injuries.

Crews from Lincoln Fire & Rescue responded to the collapse Thursday afternoon at the Ethel S. Abbott Sports Complex.

Assistant Chief Pat Borer says the cause of the collapse is under investigation. He says the balloon-like structure encompassed 80,000 square feet.

Borer says crews have searched the area and believe no one was inside at the time of the collapse. Electricity to the building has been shut off to ensure electrical wiring doesn’t pose a threat.

A staffer told the Lincoln Journal Star that she heard a loud pop before seeing the bubble collapsing.