Police have made three arrests after more than 70 people overdosed in a Connecticut city. Some 52 of the 71 overdoses happened on New Haven's downtown green, next to Yale University's campus, said Fire Chief John Alston. The first three overdoses were reported on Tuesday night and the tally steadily rose throughout Wednesday, officials said. New Haven officials said the substance was K2, a synthetic cannabinoid. The incident comes in the wake of a new report that found a record 72,000 Americans died of overdoses in 2017. One man arrested on Wednesday is suspected of a connection to some of the drugs that caused the overdoses, NBC News Connecticut reported. Dr Kathryn Hawk, an Emergency Department physician at Yale New Haven Hospital, said the K2 may have been laced with fentanyl, a potent painkiller, but police have yet to confirm this. No one has died, but two individuals were in a critical condition. Some of the people were unconscious - others were vomiting, hallucinating or experiencing high blood pressure and shallow breathing.