In a massive drug bust in California, a man and a woman have been arrested after investigators found them in possession of huge quantities of extremely lethal synthetic opioids which were enough to kill more than 50 million people, authorities said.

Andres Jesus Morales, 30, and Christine Ponce, 27, were arrested and each charged with four felony counts of possession of a controlled substance for sale after 46 pounds of illegal drug "Carfentanil" was seized from a home in Perris, the River Side's District Attorney's office said in a news release last week.

Carfentanil is a highly regulated synthetic opioid that is typically used for tranquilizing elephants and other large animals. The drug is not approved for use on humans and should be handled with extreme care as it can be absorbed through the skin or can get accidentally inhaled as airborne powder, according to the Drug Enforcement Administration.

"It is 100 times more powerful than fentanyl and 10,000 times more potent than morphine. If mixed in with other drugs, the 21 kilos of carfentanil seized could have been enough to potentially kill more than 50 million people," the news release stated.

Fentanyl is fatal at two milligrams while a lethal dose of Carfentanil is unknown. Carfentanil is believed to be fatal even at the nanogram level.

Investigators said it is likely to be the largest seizure of carfentanil in Riverside County.

In addition to carfentanil, 8.8 pounds of cocaine, and 2.2 pounds of heroin were also seized from the house while the investigators executed a search warrant on Aug.17. No one was at the residence during the search, but the police said they identified Morales and Ponce, believed to be a couple, as suspects in the case. They were arrested after a month-long investigation, the officials said, according to USA Today.

Morales and Ponce are believed to be part of an opioid drug ring in Riverside County, according to The Press-Enterprise. The two are being held without bail after they were arraigned in court for a preliminary hearing on Sept. 23 where they pleaded not guilty to charges. They are scheduled to appear again in court on Nov. 9.

drugs-908533_1920 Representation. Drugs and money. Photo: Pixabay