UPPER DARBY, Pa. (AP) — Authorities say four family members were arrested after stripping naked outside a suburban Philadelphia high school and chanting "God is great."

Upper Darby police say it happened around 1 p.m. Friday in a parking lot outside school.

Police Superintendent Michael Chitwood says investigators don't know why 44-year-old Sarah Butler and three of her children — 23-year-old Joanne Butler, 22-year-old Bessie Butler and a 14-year-old son — decided to disrobe.

He says the mother had gone there around 10 a.m., demanding to see a student. After she was denied admission, Chitwood says the family lay on the ground and began chanting, eventually shedding their clothing.

Chitwood says the adults will be charged with defiant trespass, disorderly conduct and open lewdness. A telephone listing for them could not be found.