A corporate helicopter plunged into the East River (search) just blocks south of the United Nations on Friday, the second helicopter crash in four days in the waters off Manhattan. Rescuers pulled all eight on board out of the choppy water.

One of the pilots took salt water into his lungs and was in critical condition, authorities said. The other seven were in good condition and were expected to be released Friday night.

Two pilots and six businessmen were aboard the Sikorski S-76 (search) when it went down seconds after taking off from the 34th Street heliport. The chopper made it barely one block north before it suddenly tumbled tail-first into the water.

The cause of the crash was not immediately known. The helicopter sank afterward, and police scuba divers were searching for the wreckage.

Three of the victims had been swept by the current more than a dozen blocks south before they were rescued, apparently by a private vessel.

The six passengers worked for MBNA Corp. (search), based in Wilmington, Del. The helicopter was registered to MBNA and was believed headed for Wilmington.

Witness Thomas Overby, 48, said the helicopter appeared to take off normally before something went wrong. Once it hit the water, Overby spotted men in business suits screaming "Help!" as they bobbed in the river.

The Federal Aviation Administration (search) did not immediately return a call for comment.

On Tuesday, another helicopter crashed into the East River shortly after takeoff for a sightseeing flight. Six tourists and the pilot were hospitalized.

One of those hurt in the earlier crash, Karen Butler, of Essex, England, remained in serious but stable condition at Bellevue Hospital on Friday.