(CNN) - — The third and final day of New York City's Electric Zoo music festival was canceled Sunday after two concert-goers died and at least four others were hospitalized due to drug-related causes, according to Sgt. Lee Jones of the New York Police Department.
The cause of death for the two concert attendees -- a 23-year-old male and a 20-year-old female -- is believed to involve the drug MDMA, either in Ecstasy pills or in its "pure" powder or crystal form, known as molly. Four others remain hospitalized and critically ill, with the causes still under investigation, Jones said.
Ellen Borakove, spokeswoman for the New York City Office of Chief Medical Examiner, told CNN an autopsy is scheduled for one of the victims and that she expected to have more information Sunday afternoon.
The city recommended the electronic music festival be canceled after the recent events, and the event's promoters, Made Event, agreed, Jones said.
In a statement posted Sunday on the event's homepage, Made Event 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."
Social media postings regarding Electric Zoo's cancellation vary from sympathetic to downright infuriated.
General admission passes cost $179 per day for the festival, held at Randall's Island Park in the East River. Organizers said information on the refund process would be posted soon.
"Large bags," "bad attitudes" and "illegal substances" are among the 22 listed types of items prohibited at the venue, and everyone is searched upon entry, according to the website.
Founded in 2009, Electric Zoo features electronic dance music. Over 110,000 people attended the festival last year. The three-day festival started on Friday and was scheduled to run till Sunday from 11 a.m. to 11 p.m. each day.