Aviation authorities say the pilots aboard the commuter plane that crashed outside Buffalo, New York, discussed icing problems on the windscreen and wings with the control tower. Moments later the aircraft went down in a residential community killing all 49 persons aboard and one person on the ground.

Moments before Continental Airlines flight 3407 fell out of the sky and crashed into a house on a quiet street in the suburban town of Clarence Center, the pilots told the control tower at the nearby Buffalo Niagara International Airport that they were experiencing ice build up on their wings and windshield causing the plane to severely "pitch and roll." They are heard here in audio provided by LiveATC.net, an air traffic website.

Aviation investigators recovered the flight's "black box" voice and data recorders earlier Friday and sent them to Washington for analysis.

National Transportation Safety Board spokesman Steve Chealander told a news conference that investigators are not ruling anything in or out yet in terms of the cause of the crash.

Flight 3407 was en route from Newark, New Jersey when it came down about nine kilometers from the Buffalo airport. It was due to land there shortly after 10 p.m. Thursday evening (local time). There was a light snow and moderate winds in the area at the time.

President Obama offered his condolences to the families and friends of those killed. He paid a special tribute to one victim whom he had met just days ago. Beverly Eckert lost her husband, Sean Rooney, in the September 11, 2001 terrorist attacks on the United States. Since then, she had been an advocate for other families who lost loved ones on that day. "In keeping with that passionate commitment, she was on her way to Buffalo to mark what would have been her husband's birthday and launch a scholarship in his memory. She was an inspiration to me and to so many others, and I pray that her family finds peace and comfort in the hard days ahead," he said.

Also aboard flight 3407 was Alison Des Forges, a human rights expert who was considered one of the world's leading experts on the genocide in Rwanda.

Thursday's crash was the first fatal crash of a commercial airliner in the United States since August 2006, when 49 people died in the state of Kentucky.