Story highlights At least a dozen overdoses and four deaths have occurred over two days in south and central Georgia

Reports of an unidentified yellow pill have state officials on the lookout for new street drugs

(CNN) At least a dozen people were hospitalized over 48 hours in central and south Georgia after swallowing an unidentified street drug, according to state and hospital officials. Four deaths have been linked to the overdose cluster, but officials are still waiting on autopsy results to determine the exact cause of death.

A day later, on Wednesday, six more overdoses were linked to the pills, whose contents are being analyzed by the Georgia Bureau of Investigation, according to a release by the Georgia Department of Public Health.

"What is uncommon is to see so many (overdoses) come in in such a short time frame," said Dr. Christopher Hendry , chief medical officer of Navicent Health, one of three hospitals in Georgia that is known to have received the patients.

Counterfeit pills resembling the prescription painkiller Percocet have caused mutiple overdoses in Georgia.

Some patients have described taking a yellow pill they thought was the prescription painkiller Percocet, Hendry said, but the overdose symptoms were "much more severe in onset."

The word "PERCOCET" had been stamped in capital letters on one side of the pills, the Bibb County Sheriff's Office said in a statement on Wednesday. On the other side, the pills are imprinted with the numbers "10/325" -- usually an indication of medication dosage. Investigators noticed that the imprints on the counterfeit pills were made "at an angle" and not as deep as the manufacturer's pills.

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