Authorities say more than 100 people in New Haven, Connecticut, have been taken to area hospitals this week for suspected drug overdoses linked to a synthetic version of marijuana.

No new cases had been reported as of Friday morning, according to local news station News12. There have been no fatalities. 

Authorities suspect K2, a manmade cannabinoid, is to blame for the incident that appeared to begin late Tuesday. It was initially suggested that the substance may have been laced with an opioid, but Drug Enforcement Administration tests conducted so far have not indicated that is the case. Some victims, however, had the opioid fentanyl in their systems in addition to K2.

New Haven police said Wednesday a man “known” to authorities who was out on parole had been arrested as a person of interest in the mass overdoses. Two others were later arrested in connection with the incidents. At least one individual is suspected of handing out samples of the drug for free.

“Even though it is something that is being hailed as ‘synthetic marijuana’ and most people think that you can’t overdose on marijuana, clearly in this case you can, and we want people to stay away from this,” New Haven Police Chief Anthony Campbell said Friday morning.

At least 76 people overdosed in just one 24-hour period, according to ABC affiliate WTNH. Among all the cases, at least two suffered severe symptoms, authorities said.

“We’ve heard from people on the green that it potentially included PCP. Some of the reactions in the emergency room would suggest that there was an opioid involved as well,” Emergency Medical Services Medical Director Dr. Sandy Bogucki told reporters Wednesday. 

“There were some that were unconscious, some that were nauseous, lethargic, some in respiratory duress,” New Haven Fire Chief John Alston said of the people treated by emergency responders.

“Nationwide, this is an issue for every city, every agency,” Alston said.

Only a few people had fallen ill late on Tuesday, but by Wednesday afternoon, well over a dozen more around the city required medical assistance, the New Haven Register reported. The number continued to climb Thursday. 

“It’s not unusual to see a large group of people overdosing, but not at this alarming rate,” Officer David Hartman, a spokesman for the New Haven Police, told The New York Times.

This story has been updated to reflect that more people have overdosed in New Haven, as well as with comment from Campbell, information about additional arrests, and the results of the DEA tests on the drug.