The president started as "consoler-in-chief" as he addressed the nation, but quickly pivoted into political blame, writes the BBC's Anthony Zurcher.

A pair of young figure skaters, their mothers, and two Russian coaches were among the 60 passengers on board the jet.

The aircraft collided with a military helicopter that was on a training flight as it approached the runway.

They include two teenagers, their mothers and two former Russian stars, according to their club in Boston.

Experts say the deadly incident poses grave questions about how a collision was able to happen over the US capital.

No survivors are expected after a plane with 64 people on board hit a helicopter carrying three soldiers.

Audio from moments before collision captures controllers asking the military helicopter if it has seen the passenger jet.