A threat to safety has led to a lockdown at Stony Mountain Institution.

Assistant warden Guy Langlois says a full-scale, “exceptional search” got underway Friday morning.

He wouldn’t provide details, but says these searches only take place when there is “a clear and substantial danger to the safety and security of the institution, its staff, inmates or the public.”

Visitations are suspended until the search is complete.

Langlois couldn’t provide an estimate of when that will be.