COLUMBIA, S.C. -- Police on Wednesday were investigating how a naked couple fell four stories from the roof of a downtown office building to their deaths.

The man and woman were found near the sidewalk by a passing cab driver around 5 a.m. Wednesday. One person was pronounced dead at scene and the other died a short time later at a local hospital.

Clothing was discovered on the roof, leading authorities to suspect the couple, in their early 20s, may have been having sex. Their identities were not released.

"It's too early to rule out anything," Columbia police Sgt. Florence McCants said, but McCants said a preliminary investigation didn't show any sign of foul play.

The roof of the building is pyramid-shaped.