The three-day Electric Zoo Festival in New York City has been cancelled following two fatalities apparently involving the drug MDMA.

At least four concertgoers became critically ill and were placed in critical care units in area hospitals, with Jeffrey Russ, 24, and Olivia Rotondo, 20, dying as a result. According to the New York Times, Russ was reportedly attending the festival with 23 members of his Syracuse University fraternity. 

The final day of the festival was cancelled by the city' government "due to serious health risk," with the concert promoters in agreement.

"During the first two days of the Electric Zoo music festival, two concert-goers have died and at least four others became critically ill and have been placed in intensive care at area hospitals," said a statement, "Definitive causes of death have not yet been determined, however, both appear to have involved the drug MDMA (ecstasy, or molly). The Electric Zoo organizers have worked with City officials to reduce health risks at this event, but in view of these occurrences, the safest course is to cancel the remaining day of the event."

In a statement on the Electric Zoo website, the promoters said: "The founders of Electric Zoo send our deepest condolences to the families of the two people who passed away this weekend. Because there is nothing more important to us than our patrons, we have decided in consultation with the New York City Parks Department that there will be no show today."

Artists slated to play the Electric Zoo on Sunday included Armin Van Burren, Steve Aoki, Diplo, and Krewella, while Avicii, Benny Benassi, David Guetta and Tiesto have played sets on the first two days.

David GuettaDavid Guetta Performing At The Royal Albert Hall

Tiesto Played Electric Zoo Before The Event Was Cancelled