Death toll climbs in killer US snowstorm

A killer snowstorm that has killed 13 people in western New York state could be followed by severe flooding next week, authorities say.

The death toll has risen to 13 from a killer snowstorm in western New York state where rising temperatures and heavy rain will compound misery by causing severe flooding into next week.

Blizzards dumped a year's supply of snow in just days south of Buffalo city, bringing down 30 buildings, imperiling mobile homes and paralysing communities.

Erie County chief executive Mark Poloncarz said on Friday that 13 people had died and warned further deaths could not be ruled out as rescue workers continue to dig out vehicles trapped in the snow.

The latest fatalities were two elderly people who died during and immediately after being evacuated from a nursing home, and a 50-year-old man found dead in his vehicle.

The National Weather Service says "lake effect snow," created when frigid air moves over warm lake waters, remains a risk.

New York state Governor Andrew Cuomo has warned against unnecessary journeys as conditions remain perilous.

Improving weather will allow for the massive snow removal effort to quicken pace, with the National Guard bringing in extra people and the arrival of additional equipment.

Cuomo, who has declared a state of emergency, said he had spoken to the White House on Thursday and a full damages assessment could yet prompt a federal disaster declaration.

Poloncarz described "Winter Storm Knife" as one of the worst he could remember and said the worst-hit areas had been affected more than during the deadly blizzard of 1977.

"Now we have to be prepared for the flooding. There will be flooding in all likelihood starting on Sunday," he said.

Buffalo Mayor Byron Brown said 1600 trucks have already carted 32,000 tons of snow out of south Buffalo.