Update, 5:10 pm: The female crash victim recovered from the East River has been pronounced dead.
Update, 4:55 pm: The missing passenger in a helicopter crash has been found, but the female victim's condition is unknown.
NBC reported that the helicopter was carrying four tourists from England along with the pilot. One passenger was still missing over an hour after the aircraft made impact. Initial reports said the crash took place at 3:22 p.m. Tuesday.
NYPD spokesman Paul Browne told NBC News that the helicopter had just taken off from the 34th Street heliport and was attempting to return to the heliport when it crashed in the river.
The helicopter does not have floating devices installed, and sunk immediately and rapidly.
An earlier CBS report said that two female passengers had been taken to NYC's Bellevue Hospital in cardiac arrest, and a male passenger -- possibly the pilot -- was taken to NYU. IBTimes is working to verify if these reports are still current.
Dan Sweeney, a manager at the NYC Water Club, witnessed the accident.
It went down pretty fast, you could see the splash, you could see the top of it and it just disappeared, he told NBC. It looked like it was trying to land at the heliport and missed the landing.
East River ferry service is suspended between 34th street and points in Brooklyn and Queens.
A representative from the U.S. Coast Guard told CBS that rescue efforts will go on as long as it takes, and that conditions are favorable for a search and rescue effort.