VALHALLA, N.Y. (CBSNewYork/AP) — Six inmates at Westchester County Jail reportedly all overdosed, police say.

Westchester County Police spokesman Kieran O’Leary told The Associated Press Sunday that police are now investigating how the drugs ended up in the county’s jail in Valhalla.

Correction officers first discovered one of the inmates in medical distress shortly before 6 p.m. and then realized five more were suffering similar symptoms.

O’Leary said they all showed signs “of a possible drug overdose.”

Emergency medical crews were called to the hospital and the six were taken local hospitals. All are listed in stable condition, according to police. Their identities were not released.

Although investigators suspect what may have caused the prisoners to fall ill, they are still working to determine what type of drug the inmates may have used.

O’Leary said police have launched a formal investigation to identify the substance and figure out how it was brought into the jail.

(TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)