At least 46 people have overdosed at or near a park that runs alongside Yale University from a suspected bad batch of K2 synthetic cannabis, authorities have said.
Paramedics and police officers remained at the parkas more people fell ill.
This isn't the first time the city has seen a mass-overdose - a New Haven man pleaded guilty to charges in connection with overdoses of more than a dozen people in June 2016. Some victims tested positive for the powerful opioid fentanyl, but it appeared most if not all the overdoses were caused only by a potent batch of "K2" synthetic marijuana, said Dr. Kathryn Hawk, an emergency medicine physician and professor at Yale-New Haven Hospital, where numerous victims were treated.
Two of the ODs were life-threatening, and some people did not respond when the anti-overdose medication Naloxone was administered, he said.
"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.
The man arrested on Wednesday is suspected of being connected to some of the drugs that caused the overdoses, NBC News Connecticut reported.
The Office of Emergency Management in New Haven said it is still fielding calls and the number of victims could increase. "Don't put your life in harm".
During the news conference live streamed by WTNH News 8, first responders rushed to treat a nearby victim. "Let's address it that way", Alston said.
Marcelo: Vinicius Jr the present and future of Real Madrid
Ahead of the start of La Liga 2018-19 season, a bullish Sergio Ramos downplayed the effect of Ronaldo's departure from the club. Here, Sports Mole looks at how Bale has fared against Atletico in the past.
The substance behind these overdoses is highly unsafe and must be avoided.
Officials were testing the blood of victims to determine what exactly triggered their symptoms.
Gov. Dannel P. Malloy said the state departments of Public Health and Mental Health and Addiction Services were helping New Haven officials.
"Today's emergency is deeply troubling and illustrative of the very real and serious threat that illicit street drugs pose to health of individuals", the Democratic governor said in a statement. The city also saw more than a dozen synthetic marijuana overdoses in late January.
The latest incident in CT comes as new preliminary estimates on 2017 overdose deaths were released by the Centers for Disease Control and Prevention.
So far, no deaths have been reported. In recent months, K2 has caused hundreds of people in about 10 states to be hospitalized, sometimes with severe bleeding.
In a warning last month signed by top federal officials, the Food and Drug Administration said synthetic marijuana has become particularly risky because some producers have been adding brodifacoum - a long-acting anticoagulant thought to extend the drug-induced "high".