NEW HARTFORD, N.Y. — To its neighbors in this upstate town, Word of Life Christian Church presented itself as a constant curiosity: an imposing but tidy former schoolhouse whose occupants kept to themselves, almost never opening their doors or their mouths, secluded behind a closed entrance.

Over the last three days, however, the inner life of that secretive sect suddenly spilled into the outside world. On Sunday evening, the authorities said, two teenagers — brothers and the sons of two members of Word of Life — were called into a sanctuary and savagely beaten by at least a half-dozen people, including their parents and older half sister.

“Both brothers were continually subjected to physical punishment over the course of several hours, in hopes that each would confess to prior sins and ask for forgiveness,” Chief Michael S. Inserra of the New Hartford Police Department said at a news conference on Wednesday.

It is not clear what those sins were, but for several hours, into Monday morning, punches and kicks landed on the brothers’ stomachs, genitals, backs and thighs, as the so-called counseling session turned into a case of manslaughter and assault.