Tornadoes reported in Texas, Oklahoma as powerful storms slam the Plains

A severe storm system was unleashing powerful winds and triggering tornado warnings for Texas, Kansas, Missouri and Oklahoma as it lashed the Plains over Sunday night.

The big picture: Damage to buildings and widespread power outages were reported in Oklahoma after the National Weather Service confirmed a tornado had struck the city of Norman late Sunday. There were reports of a suspected tornado in Mclean, east of Amarillo, Texas, earlier in the evening.

• The NWS said parts of the Southern Plains into the Middle Mississippi Valley could see "a higher threat of wind gusts of 65 knots or greater, two-inch or greater hail" and tornadoes on the Enhanced Fujita Scale of EF2 to EF5 — the highest tornado rating in this category, which means there could be "incredible damage" from gusts of over 200 mph.

Details: The Norman Police Department tweeted early Monday that officers were "on scene for storm damage in the south/east side of Norman" and were "assessing potential injuries and the extent of all the damage."

• "There are multiple roads closed secondary to downed power lines and debris" in the area, the NPD added.
• The local NWS tweeted that the tornado had passed near its Norman office and warned the threat of "damaging winds and possible embedded tornadoes" would continue as the storms moved east over Sunday night.

Between the lines: Embedded tornadoes were anticipated in the forecast derecho — which would bring hurricane-force "widespread damaging winds and embedded swaths of significant severe gusts from 80-110 mph, centered on parts of Oklahoma" over Sunday night.

Of note: NWS describes a derecho as a "very long lived and damaging thunderstorm with a wind damage swath that extends more than 240 miles and has wind gusts of at least 58 mph or greater along most of the length of the storm's path."

By the numbers: Nearly 71,800 customers were without power early Monday, per Poweroutage.us. Outages were also reported among almost 42,000 customers in Texas, according to the utility tracker.

• Some 68 million residents were within a high wind warning or advisory due to the threat of "widespread damaging winds" from the southern Plains to the Ohio/Tennessee Valley from Sunday afternoon through Monday night, the NWS said.

What else to expect: "The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes," the NWS said in a forecast update early Monday.

• "In addition, there is a marginal Risk of excessive rainfall over parts of the Central Plains into the Upper/Middle Mississippi Valley through Monday morning. The associated heavy rain will create localized areas of flash flooding, affecting areas that experience rapid runoff with heavy rain."

Editor's note: This is a breaking news story. Please check back for updates.