Snow-laden western New York state braced for another wintery onslaught today, while in communities from the US Midwest to the Northeast storms closed schools, hit motorists and knocked out power.

A written bomb threat was discovered on a flight from Seattle to Chicago, prompting US aviation officials to temporarily close Midway Airport.

A jetliner trying to land in heavy snow slid off a runway, crashed through a boundary fence and slid into a busy street, hitting one vehicle and pinning another beneath it yesterday. A child in one of the vehicles was killed.