Severe storms with tornadoes and heavy rains took aim Monday at the Southern Plains, mainly parts of Oklahoma and Texas, where five and half million people were likely to be affected. The latest threat follows a weekend of storms that spawned numerous tornadoes from Texas to Nebraska.

Late Monday afternoon, CBS affiliate KWTV reported that a tornado touched down in Crescent, Oklahoma, north of Oklahoma City. Earlier, the station spotted a tornado in nearby Kingfisher County.

The National Weather Service had said Oklahoma City was at "high risk" of tornadoes and severe thunderstorms, and school districts in the Oklahoma City area canceled classes for more than 150,000 children Monday as a precaution. CBS News correspondent David Begnaud reports school was also canceled in Moore, Oklahoma, where a deadly tornado in 2013 killed 24 people, including seven children at an elementary school.

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According to CBS News weather producer David Parkinson, the severe weather index in Oklahoma City was 5/5 — the first 5/5 index anywhere in the U.S. in just over two years, and the first in Oklahoma City in eight years. The Oklahoma City metro area was facing six to 10 inches of rain and there was a high risk of a tornado outbreak, with a powerful EF-4 or EF-5 tornado considered likely. A flood watch was in effect for the greater Oklahoma City region, while strong winds and hail were forecast for West Texas.

A map from the National Weather Service shows parts of Texas and Oklahoma, including the Oklahoma City area, at "high risk" of tornadoes and severe thunderstorms on May 20, 2019. National Weather Service

The National Weather Service said the storm system would move later Monday into western Arkansas. The threat of severe weather would continue into Tuesday.

Forecasters said four tornadoes struck parts of West Texas this weekend, damaging some homes and businesses. The National Weather Service on Sunday reported two tornadoes hit parts of San Angelo a day earlier, and twisters were also reported Saturday in Ballinger and Abilene.

Meteorologist Terry Huber in San Angelo said Sunday that officials had no reports of anyone hurt in twisters from the same storm system. Huber estimated winds topping 111 mph hit San Angelo, damaging homes and businesses and downing power lines.

Furthermore, according to a climate map produced by the National Weather Service, as of Monday morning most of Oklahoma and Kansas were under a flood watch due to heavy rains, while most of Texas was under a wind advisory, which means sustained winds of 30 mph or higher or wind gusts exceeding 40 mph.

In Louisiana, a possible weekend tornado damaged or destroyed at least 50 homes and businesses. The Monroe News Star reports numerous trees were toppled and utility poles snapped and more than 6,500 residents in Ville Platte, a city about 75 miles northwest of Baton Rouge, were left without power.