The Drug Enforcement Administration (DEA) has issued a warning about an increase in counterfeit pills laced with fentanyl that are made to look like real prescription medications.

The pills are sold online or on the street, the agency said. The pills are made to look like real prescription medications such as OxyContin, Percocet, Vicodin, Xanax or Adderall. The DEA has seized more than 9.5 million counterfeit pills so far this year — more than the previous two years combined, NPR reports. The DEA’s lab has found that two out of every five counterfeit pills with fentanyl contain a potentially deadly dose of the substance.

“The United States is facing an unprecedented crisis of overdose deaths fueled by illegally manufactured fentanyl and methamphetamine,” DEA Administrator Anne Milgram said in a news release. “Counterfeit pills that contain these dangerous and extremely addictive drugs are more lethal and more accessible than ever before.”