A lockdown and sweep of the Westchester County Jail in Valhalla was ordered Monday night by County Executive Rob Astorino after four more inmates were rushed to the hospital after apparent drug overdoses.

The inmates were rushed to Westchester Medical Center, authorities say, after exhibiting symptoms of a drug overdose including vomiting.

All four inmates were in the section known as the "old jail."

Correction officers on duty earlier Monday afternoon were brought back in, along with the Department of Corrections medical director.

Authorities say that they are going cell to cell, checking inmates to make sure no one else is sick.

On Sunday, six inmates were taken to the hospital after apparent overdoses. Sources say the cause is likely K2 or Spice, a synthetic form of marijuana.

Two inmates involved in Sunday's apparent overdose have been charged with promoting prison contraband. One inmate was found with a hand-rolled cigarette and the other was allegedly found with a plastic bottle re-configured into a pipe for smoking.