The afternoon's landing in Jamaica Bay was rough enough to cause a rotor to snap and dent the windshield.
The crew was made up of a pilot, co-pilot, crew chief, two scuba divers and a crew chief in training.
The emergency landing occurred as the chopper was approaching an NYPD air field bordering Jamaica Bay in Brooklyn. The crew deployed flotation devices before touching down.
A harbor unit and two private boats pulled the officers off the aircraft as it floated upright.
"The pilot stated that she heard a loud band, it was coming in for a landing, the helicopter dropped rapidly and landed in the water, she has, as is normal procedure, operated the floatation devices so that when the helicopter hit the water, those floatation devices deployed," NYPD Commissioner Ray Kelly said.
The cause of the emergency is unknown. Police spokesman Paul Browne says investigators suspect mechanical failure.
The helicopter is a Bell 412 Air Sea Rescue Helicopter. The NYPD purchased two of them from Bell Helicopter out of Texas in 2009.
The helicopter was part of the NYPD's UN General Assembly security detail.
The crew was able to send out a mayday shortly before they landed.
An NYPD harbor vessel and a couple of civilian boats responded to the scene.
"When I got on the scene, I saw the helo was floating, the floatation was deployed, there was another police vessel on the scene removing the people from the copter," said Captain Jack Schachner, a tow boat operator.
The six officers never entered the water. They got on the NYPD boat and were transported to Lutheran Medical Center for evaluation.
They suffered mainly neck and back injuries, with some lacerations, likely from the broken windshield.
They have since been released from the hospital.
There have been no problems with this particular helicopter before.
Browne called it "very reliable."
The NYPD has six other helicopters in their fleet.