Six people overdosed at a home late Saturday at a home South St. Paul, with most of them unconscious and not breathing at one point, police said Sunday.

The incident occurred shortly before 10:30 p.m. at a house in the 200 block of Bircher Avenue, police said.

Lifesaving efforts, including the use of the opioid antidote Narcan, were used by emergency personnel, said Police Chief Bill Messerich.

All were hospitalized, and there is no word so far on how they are faring, Messerich said.

"At this time we believe the cause was an accidental overdose from an unknown substance," the chief said.

"The vast majority" of the six were unconscious and not breathing when officers arrived, Police Sgt. Cory Slifko told KSTP-TV, Channel 5.

An officer from an unspecified assisting agency was transported to the hospital with symptoms related to exposure to the substance, the chief said. The officer has since been released from the hospital.

Assisting in this incident were police from West St. Paul and Inver Grove Heights, and personnel from the South Metro Fire Department and Health East ambulance service.