US President Joe Biden announced federal disaster relief for New York state on Monday after a severe winter storm left at least 27 people dead in the Buffalo area and thousands more without power.

Specifically, the Federal Emergency Management Agency (FEMA) has been authorized to coordinate efforts in the greater Buffalo metro area.

Biden spoke with Governor Kathy Hochul late on Monday night to offer "the full force of the federal government" to support emergency efforts in the state.

"My heart is with those who lost loved ones this holiday weekend. You are in my and Jill's prayers," Biden tweeted earlier in the day.

A 'once-in-a-lifetime' storm

More than 4 feet (1.2 meters) of snow fell on western New York state in what Hochul has called "an epic, once-in-a-lifetime" catastrophe.

Hundreds of National Guard troops were deployed to assist emergency personnel on Monday. However, roads remain littered with cars and even plows burred under snow, complicating rescue efforts.

Hochul said the wild weather go down in history as "the Blizzard of '22" and added that it is "way too early to say this is at its completion."

Local officials ranked it as the worst Buffalo-area snowstorm since a 1977 blizzard that killed nearly 30 people.

Authorities probe flight chaos

Other parts of the US are also being battered by the wild winter storm, which has left as many as 60 people dead nationwide.

Snow, wind and freezing temperatures forced the cancellation of some 15,000 US flights in recent days, including more than 3,800 on Monday, according to tracking site Flightaware.com.

However, late on Monday, the US Department of Transportation said it would investigate the "unacceptable" number of Southwest Airlines flights that had been cancelled or delayed to determine if they were in the airline's control.