AUSTIN (KXAN) — Police said they are still working to determine what drug led to two overdose deaths and at least a dozen hospitalizations during an alarming 48-hour period this past weekend.

Assistant Chief Jerry Bauzon with the Austin Police Department announced Tuesday afternoon undercover officers will work during South by Southwest to crack down on drug sales. He said the U.S. Drug Enforcement Administration (DEA) is now assisting with the investigation into counterfeit drugs potentially contributing to this increase in overdoses recently.

“Right now basically you have some mad chemist in the garage making these pills,” Daniel Comeaux, the special agent in charge of the DEA’s Houston division, said at a news conference. “It’s not pharmaceutical companies. It’s not a doctor prescribing them. It’s individuals literally in the garage with a $10 machine putting together these pills, so there’s no true medical use for them, and it’s causing overdose.”

Police said they could not confirm at this time if opioids mixed with Xylazine, a veterinary muscle relaxer, caused the uptick in overdoses. However, before these happened, paramedics with Austin-Travis County EMS received a warning about its presence in the community from the Office of the Chief Medical Officer. Capt. Darren Noak with ATCEMS said it “was kind of a coincidence in a way” the medical advisory went out around the same time the deadly overdoses happened.

“Xylazine is in our area,” Noak said. “Our Office of the Chief Medical Officer was trying to make our medics aware of that drug.”

He explained paramedics could still use Narcan, also known as naloxone, to treat an overdose from Xylazine, but he said it does present some additional challenges.

“What we’re seeing is that it takes a lot more dosage of the naloxone, the Narcan, to bring them back to a state where they’re breathing on their own, and their respiratory state’s back to normal,” Noak said.

During a news conference Monday about safety preparations for SXSW, Police Chief Joseph Chacon reminded the community every officer on patrol is equipped with Narcan now. Bauzon said Tuesday officers have used the overdose reversal drug to save several people in the community.

“It’s an invaluable tool, and I believe it’s beneficial,” Bauzon said.