A Helicopter that crashed into the Hudson River is lifted on to the deck of a boat (Reuters)

A helicopter crashed into the Hudson River in New York City on Wednesday shortly after taking off from Manhattan, causing minor injuries to the pilot and a dockworker, police and fire officials said.

Dramatic video footage of the incident shot by witnesses and posted on social media showed the helicopter spinning seemingly out of control over the Hudson near 30th Street, before plummeting into the water.

"Relieved to report there were no deaths or serious injuries after a helicopter incident on the Hudson river. Thank you to our first responders for your quick action," New York Mayor Bill de Blasio said on Twitter, urging residents to avoid the area.

New York police officials told a news conference that the 34-year-old pilot suffered an injury to his left hand. No one else was on board.

A dockworker injured his right wrist after he fell while scrambling to get out of the way of the plunging aircraft, police said at the press conference.

A deckhand on ferry crossing the Hudson, Edwin Montoya, pulled the pilot out of the water after witnessing the crash, its captain said in a statement released by the ferry company, NY Waterway.

"It was just instinct. Just another day for NY Waterway rescues. We're right here. Edwin Montoya is an outstanding deckhand. He moved instantly to the rescue," Captain Adam Sciaino said in the statement.

In 2009, US Airways pilot Chesley "Sully" Sullenberger famously landed an Airbus A320 with 155 people safely on the Hudson River off Manhattan after it struck a flock of geese and lost power.