Mudslides and flooding from rain unseen in modern records has claimed at least four lives and left 200 people missing around Boulder, Colo., according to news reports.

Rescuers are now bluntly telling people that if they do not get to safety now, they can expect to be stranded for weeks as the roads become completely useless from debris, mud and water. The long list of roads rendered impassable includes major highways like Boulder Canyon Drive and Highway 7 -- the principle routes in and out of the city.

The flood area covers an area the size of Colorado, the Washington Post reported Saturday.

Describing the flooding in terms of 100-year probabilities is almost beside the point, wrote Bob Henson of The University Corporation for Atmospheric Research, headquartered in Boulder. The 9.08 inches of rain between 6 p.m. Thursday and 6 p.m. Friday shattered Boulder’s previous 94-year-old record for wettest calendar day of 4.8 inches, he wrote. Boulder received nearly twice as much rain Thursday "as any other entire September has produced." The September record is 5.5 inches, 1940. Boulder received almost 15 inches of rain between Monday and Friday -- more than has fallen on the city since the start of the year.

Watch a news report about the flooding below.

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[Image courtesy of the Boulder County Government.]