Still images show parts of the 53.6.m American Falls covered in ice and the area below the observation area frozen over.

A deadly blast of Arctic air that shattered decades-old temperature records as it enveloped the eastern United States on Tuesday caused Niagara Falls on the United States and Canadian border to become a winter wonderland.

The cold weather caused the Niagara River to form an "ice bridge" and freeze over. Large amounts of ice up river from the falls led authorities to issue a flash-flood warning for two islands in the area, according to local media reports.

The low of minus -20.55 degrees Celsius at the National Weather Service office at Buffalo Niagara International Airport tied a record set in 1942. The wind chill dropped down to -33.33 Celsius, The Buffalo News reported.

The record temperatures were caused when polar air mass wept over North America during the past few days. Authorities had put about half of the United States under a wind chill warning or cold weather advisory.