(CNN) — A tornado tore through parts of Menasha and Appleton, Wisconsin, on Monday afternoon, damaging homes, uprooting trees and leaving thousands without power. Local authorities say they are responding to numerous storm-related calls and have urged residents to stay indoors as they assess the damage.
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The National Weather Service described the tornado as “extremely dangerous,” and issued a particularly dangerous situation tornado warning — the second-highest level warning — shortly after 12 p.m. CT.
After hitting Menasha, the tornado moved over Lake Winnebago and dissipated over water. It was observed for at least 20 minutes from near Appleton to the northern coast of the lake.
The tornado’s strength rating is at least EF-2, according to a preliminary damage survey by the National Weather Service. The survey is ongoing, and more information will be released soon.
Homes in Appleton have been completely destroyed with roofs ripped off, along with trees being uprooted and split, drone footage shows.
“If you are currently in your home or currently stuck in the area that has been damaged, we ask that you shelter in place and stay inside,” Menasha Police Chief Matthew Albrecht said during a news conference Monday.
He added that first responders from local agencies are assessing the damage and looking for victims.
Video from Menasha obtained by CNN shows homes missing parts of roofs, structures stripped of their exteriors amid piles of debris, downed power poles and uprooted trees. In one video, a vehicle is seen flipped over next to a road.
“We are aware of severe damage in broad areas. We are asking the public to stay indoors, watch out for downed power lines, do not drive around road closures, and do not drive around the area unless absolutely necessary,” the Menasha Police Department posted on Facebook Monday afternoon.
The entire city of Menasha may be without power, according to a post from Menasha Utilities, a municipally owned company. More than 15,000 customers are without power in Winnebago and Calumet counties, where Menasha is located, according to PowerOutage.us. More than 18,000 customers are without power in neighboring Outagamie County, where Appleton is primarily located.
Winnebago County officials on Monday afternoon reported extensive damage — including downed power lines and trees, and other hazardous situations — but exact details were unavailable as many roads remained impassable.
CNN has reached out to authorities for more information.
Tornadoes were not expected to be a significant threat to the area today – the first tornado warning for Appleton and Menasha came at 11:59 a.m. central time Monday. Preliminary reports from NWS Green Bay indicate that the tornado first touched down at 11:56 a.m., meaning that there was not a tornado warning in advance of the tornado, according to a CNN analysis. There was a severe thunderstorm warning issued at 11:13 a.m. that mentioned damaging winds, and the possibility of a tornado was mentioned in an update to the warning at 11:21 a.m.
Earlier Monday, a 29-year-old man was killed in Whitewater, Wisconsin, from a suspected lightning strike as storms moved across the area, according to a news release from Whitewater Fire and EMS. The man was part of a tree trimming crew for an area energy utility.
“The supervisor of the crew reported that there was a ‘loud bang and a flash’ and they believed the tree had been struck by lightning,” just before 10 a.m. local time, according to the release. Police and the Walworth County Medical Examiner are still investigating.
More than 390,000 customers were without power in Illinois, Wisconsin and Indiana as severe thunderstorms with damaging winds tracked across the region. One cluster of storms from south of Chicago into neighboring northwest Indiana was warned for wind gusts up to 100 mph.
A Level 3 of 5 risk of severe thunderstorms is in effect Monday for a large part of the Great Lakes and Ohio Valley, primarily for these powerful winds. Large hail is also a threats in these regions, but additional isolated tornadoes are possible.
This story has been updated with additional information.
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