As of 10 p.m., officials say 76 people have overdosed.
The Rev. Luk De Volder, rector of the historic Trinity Church on the Green, told the paper there were ambulances on the Green on Monday night as well. Fasano said the Green has become "a place of despair" and "no longer an attraction for families or economic development".
As of Wednesday evening, police have not identified the suspect.
"The Police Department is aware of a high number of patients that were treated since last night, including as many as six now". The majority of cases are centered on the New Haven Green.
"This was a particularly odd, rare occasion where (there was) call after call for man down, obviously with symptoms of some kind of overdose, and at the time of getting that patient packaged and transported to the hospital, we'd see another immediately fall down, right there", Jones said.
After Wednesday's surge of overdoses, the issue appeared to have quieted.
"We heard from people on the green this morning that it potentially included PCP", she said at the news conference.
"Crews were having to run and then resuscitate, and they were having to transport faster than they might normally just to turn the cars around and get them back out", Bogucki said, WFSB-TV reported.
"Do not come down to the Green and purchase this K2", city Police Chief Anthony Campbell said.
Three arrests have been made in the case, Hartman said, but officials can not say for certain if all three arrested or just one of them are directly responsible for the overdoses.
Police reportedly made one arrest Wednesday, though the charges were not clear.
The DEA has also been called in to assist in the investigation.
Police said they arrested a person of interest in connection with the mass overdose.
Hawk said the people who tested positive may have taken other drugs laced with fentanyl in addition to the synthetic marijuana, which is plant material sprayed with drugs and chemicals.
Emergency responders treated most of the victims with naloxone, which reverses the effects of the drug.
The state Department of Public Health and the Department of Mental Health and Addiction Services have been assisting New Haven officials throughout the day.
Two former addicts said nearly any drug can be sprayed on K2, or even dribbled out of eye droppers.
A similar incident occurred on July 4, when more than a dozen people in the same park were treated for sicknesses related to synthetic marijuana, The Associated Press reported.