(Reuters) - Dozens of drug overdoses, including four fatal ones, in a two-day period in Georgia appear to be linked to potentially lethal substances in opioid painkillers sold on the street, state public health and law enforcement officials said on Tuesday.

Five of the overdoses - but none of the deaths - were among people living in the same household in Bibb County, which includes the city of Macon, Gaylord Lopez, director of the nonprofit Georgia Poison Center, said by phone on Tuesday evening. The victims ranged in age from 20s to early 60s, he said.

The Georgia Department of Public Health said Tuesday that emergency responders in the central and southern parts of the state treated dozens of people over a 48-hour period. Some patients were unconscious or had stopped breathing and many had to be placed on ventilators.

“Patients reportedly purchased yellow pills alleged to be Percocet, an opioid pain medication,” the health department said in a statement.

Percocet is a brand-name drug that contains the opioid painkiller oxycodone and the analgesic pain reliever acetaminophen.

“There are presumptively now four deaths connected to this but this has not been confirmed with lab testing,” said Nelly Miles, spokeswoman for the Georgia Bureau of Investigation.

Lopez said the likely ingredients to the fake prescription pills included heroin and the more powerful synthetic opioid fentanyl, based on the effects of the pills. State officials said they would await lab tests before talking about the likely ingredients.

The health department said tests were being conducted to confirm the link between the counterfeit pills and the overdoses.

The highest concentration of overdoses occurred in or near Macon, Warner Robins, Centerville, Perry and Albany, the health department said.

“We’re afraid that this may be more widespread,” Lopez said.

The abuse of opioids - a class of drugs that includes heroin and prescription painkillers - has assumed epidemic proportions in the United States.

The federal Centers for Disease Control and Prevention said that in 2015, about 33,000, or 91 Americans a day, died from opioid overdosed.

In Europe, drug overdose deaths rose 6 percent to 8,441 in 2015, rising for the third straight year, driven by the increasing use of opioids like fentanyl, Europe’s Lisbon-based drug monitoring agency said on Tuesday.