A Peeping Tom took pictures of an 11-year-old state gold medallist swimmer and four young women inside a bathroom at the Hang Jebat Stadium in Krubong.
One victim, a 20-year-old factory worker, told police they were taking a bath together after swimming practice when they spotted a hand holding a camera-phone, recording them.
She said they only realised it when a flash appeared from the device during the 7.45pm incident on Wednesday.
They were in the bathroom near the aquatic centre of the sports complex.
When the five girls screamed, they heard the footsteps of someone running away.