Gymnastics coach Matthew Erichsen has admitted he secretly videotaped girls changing their clothes in a bathroom at the Auburn gym.

Erichsen, 37, pleaded guilty here Thursday to sexual exploitation of minors. King County prosecutors are recommending a three-year prison term when Erichsen is sentenced Oct. 17.

He was arrested in March after another employee at Washington Gymnastics found the video of the girls, ages 9 to 11.

The girls’ families are also suing Erichsen. They fear he may have sold copies of the video as child pornography.