BELLINGHAM, Wash. – An investigation is underway after a handful of inmates overdosed at the Whatcom County Jail.

Undersheriff Doug Chadwick said that an employee noticed an inmate lying unresponsive on the ground on Tuesday, February 7th.

Deputies called 911 after realizing the inmate had overdosed on an unknown drug.

A check of the housing unit later found three more inmates who were showing similar symptoms.

All four were taken to Peacehealth St. Joseph Medical Center for treatment.

Investigators determined that an unknown amount of illicit drugs had been smuggled into the jail.

However, following a search of the housing unit where the four inmates overdosed, no drugs were recovered.

Chadwick noted that a fifth person had overdosed two weeks ago in the jail but has since made a full recovery.

All inmates within the unit are now being monitored for potential overdose symptoms.