The skies over New York constantly buzz with helicopters carrying tourists, businesspeople, traffic reporters, medical teams and others. Crashes are not unheard of.

In 2009, a sightseeing helicopter of the same model and operated by the same company as the one in Sunday’s wreck collided with a small, private plane over the Hudson River, killing nine people, including a group of Italian tourists.

A crash in October 2011 in the East River killed a British woman visiting the city for her 40th birthday. Two other passengers died weeks later as a result of their injuries.

A helicopter on a sightseeing tour of Manhattan crashed into the Hudson River in July 2007, shaking up the eight people aboard but injuring no one. In June 2005, two helicopters crashed into the East River in the same week. One injured eight people including some banking executives. The other hit the water shortly after takeoff on a sightseeing flight, injuring six tourists and the pilot.

Nigro and Police Commissioner James O’Neill said the rescue operation Sunday took place in a 4 mph current in water about 50 feet (15 meters) deep, under challenging conditions.

The cause of the crash is unknown. The FAA and the National Transportation Safety Board are investigating.

Officials did not immediately release the names of the pilot or passengers or say how the passengers died.

The helicopter was recovered in the rescue operation and towed to a pier.

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This story has been corrected to show that three people died from the 2011 crash, including two who died in the weeks after the crash.