Visitation at the Lancaster County Prison has been suspended and officials expect the facility to remain closed to outsiders for the remainder of the week.
Warden Cheryl Steberger said staff are conducting a full sweep of the facility for contraband, checking all cells and common areas. A full search of this nature hasn't been done in 25 years, she said.
"It's the whole works," Steberger said.
All inmates are also being strip-searched, and 10% of the nearly 800 inmates will also be run through the prison's new body scanner.
Warden Steberger said the search was preplanned and not in response to any particular incident.
Staff from the Lebanon and York County prisons are assisting, as well as the K-9 unit of the Lancaster city police.
As of 2 p.m. Tuesday, staff had found contraband including pens, tattooing equipment and an unknown substance which they plan to test.
Legal and medical visitors are still permitted inside the facility.