A record-breaking deep freeze is heading for the north-eastern US as a swathe of the country's south remained without power after a deadly ice storm.

The frigid blast could bring “once-in-a-generation” wind chills that cause frostbite in less than 10 minutes, the National Weather Service warned.

Residents from Pennsylvania to Maine are being urged to limit their time outdoors through Friday and Saturday.

At least 10 people have died in the bad weather in the US south since Monday.

There were seven fatalities in Texas, two in Oklahoma and one in Arkansas.

Boston, which is anticipating sub-zero wind chills, is currently under a cold emergency.

Temperatures in New York City and other major cities are also expected to bottom out in the single digits (Fahrenheit, around -13C to -17C) by Saturday, although forecasters predict they will rebound by the end of the weekend.

More than 480,000 people were without power as of Thursday evening in Texas, Arkansas, Tennessee and Mississippi, according to poweroutage.us.

The ice storm in the region has forced US airlines to cancel thousands of flights, with airports in Dallas and Austin being the most affected.

By Thursday afternoon, temperatures in parts of Texas hit hard by the storm had climbed above freezing, and ice was expected to melt by Friday as temperatures keep rising.

Emergency crews in Texas have responded to hundreds of collision calls since Monday, some of which have been fatal. Three men were killed in a crash near Brownfield, south-west of the Texas city of Lubbock, according to the state's Department of Public Safety.

One person in Austin was killed in a car pileup on Tuesday, local authorities said. A 45-year-old man died on Monday in Arlington after his SUV slid into a highway guardrail, while a student died in a rollover crash in Wolfforth, according to local outlet KCBD.

A 49-year-old woman was killed while driving on an icy road north of Eldorado, Texas officials told CNN.

In the neighbouring state of Oklahoma, in Custer County, a 35-year-old driver was killed on Thursday morning in a six-car pileup on icy roads, Oklahoma Highway Patrol said, according to local media outlets.

Dallas Police Department asked people to make sure their tyres are inflated, to slow down on icy roads and to avoid using cruise control. (BBC)

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