Washington, Dec 28 (IANS): Thousands of people in the US' Pacific Northwest were without power after a massive winter storm slammed the region, dumping nearly 30 inches of snow in the Sierra Nevada region and leading to road closures in Northern California.

On Sunday afternoon, there were over 20,000 residents without power in Washington state, more than 14,000 in California and some 10,000 in Oregon, Xinhua news agency quoted PowerOutage.US as saying on Monday.

Several mountain roads were shut down on Sunday, including a 70-mile stretch of Interstate 80 through the Lake Tahoe region to the Nevada state line.

The California Department of Transportation tweeted that there was "low or zero visibility on I-80", according to a report by CBS News.

The National Weather Service (NWS) issued a winter storm warning for greater Lake Tahoe through early Tuesday morning and warned of "widespread whiteout conditions" and wind gusts that could top 45 mph.

The NWS reported 3.8 inches of snow fell in Seattle, the largest city in Washington. Frigid temperatures are expected to last in the region until Thursday.

"Record lows were set yesterday on December 26," the NWS Seattle tweeted on Monday, noting that it was minus 6.7 degrees Celsius, breaking the 1948 record of minus 5.6 degrees.

It was minus 12.8 degrees in Bellingham, where the previous record was minus 11.1 degrees in 1971.

Officials urged residents of the Seattle area to stay inside and off the roads if possible.

The NWS in Reno said snow would remain heavy as the next storm pushes through the region.

The NWS in Sacramento warned that mountain travel would continue to be difficult.