( CNN ) -- An Iowa community was shut down much of Sunday afternoon while emergency crews remained hard at work , sifting through wreckage caused by a wave of powerful tornadoes that swept across the state overnight . The twisters caused major damage to about 60 % of Mapleton , a city of about 1,200 residents , Monona County Sheriff Jeff Pratt told reporters Sunday . It was all part of a violent storm system that struck overnight , originating in eastern Nebraska and following a warm front across northern Iowa , according to National Weather Service meteorologist Frank Boksa . But despite causing extensive damage , it did not lead to any fatalities , said Stefanie Bond , a spokeswoman for Iowa 's Homeland Security & Emergency Management Division . Wildfires in Texas | Flooding in upper Midwest . Mapleton was among the hardest-hit areas . Initially , concerns about a gas leak had prompted all nonresidents to be barred from the community , which is about 45 miles southeast of Sioux City . By 5 p.m. , people were being allowed back in , though authorities remained on the scene , according to the sheriff 's department . The high winds tossed cars and tractors , tore off roofs , caused a car wash to collapse , uprooted trees and downed power lines . Yet Pratt said there had been only minor injuries , giving credit to advance warning as well as an emergency response effort that included authorities both local and from elsewhere . `` There was major devastation to the southwest portion of town , but no fatalities , '' the sheriff said . Iowa Gov . Terry E. Branstad issued a disaster proclamation for Monona County , according to a statement from his office . The proclamation allows officials to use state funds to help . He later issued a similar proclamation for Pocahontas County , which also suffered severe damage . He then toured the tornado-ravaged town on Sunday afternoon , posting pictures online of uprooted trees and conversations with residents . On his Twitter page , Branstad wrote , `` Please keep the victims in your thoughts and prayers . '' The twisters struck just before midnight Saturday . Amateur video recorded by storm chasers shows a large funnel cloud spinning across a flat terrain outside Mapleton . In the background , a passenger can be heard exclaiming , `` It 's going to hit that town ! ... Mapleton 's in big trouble ! '' Did you witness the storm ? Share your story . Afterward , National Guard troops were brought into the area , according to Stefanie Bond , a public information officer for the state 's Homeland Security & Emergency Management Division . She also said that natural gas service was temporarily shut off in the city . The Red Cross was also on the ground providing assistance . Bruce Spence , a government liaison for the group , called the damage to the town `` extensive . '' `` The whole town is without power . Main Street is a disaster , '' he told CNN . `` They 've shut down the town . As we speak , I 'm looking down one of the residential streets . There 's debris all over , trees are down . `` This is n't going to get fixed soon , '' Spence said . The National Weather Service in Des Moines , Iowa , reported tornado sightings by storm chasers and trained spotters in as many as 11 towns and cities in northern and west-central Iowa over a four-hour period Saturday night . At least three of the twisters , including the Mapleton tornado , caused significant damage , according to Boksa . In Early , a town of 1,600 residents , a tornado ripped roofs off buildings and homes and uprooted large trees , authorities said . There were no reports of injuries in that town . In Schaller , a twister knocked down a dozen trees and felled multiple power poles , the weather service reported . Tammie Pech , a Red Cross spokeswoman , said the agency was opening shelters in Mapleton and Early to take in storm victims . Only four people slept in the Mapleton shelter overnight Sunday , Spence said . Most displaced residents opted to stay with family and friends , he said . The National Weather Service also reported major damage in Nemaha , possibly from a tornado . Bond noted that strong winds also tore through hog pens in Pocohontas Country , in central Iowa , and Kossuth County , in the east along the Illinois border . Three cities in Fayette County -- Fayette , Westgate and Maynard -- were without power for about an hour Sunday evening due to a blown transformer , the state 's emergency management spokeswoman said . Randy Frank , Fayette County 's homeland security and emergency management coordinator , said that the challenges continued well after the tornadoes came through , with sustained winds blowing at least 50 mph into Sunday evening . `` Our biggest problem right now is fuel fires out of control , '' said Frank , whose county is about 255 miles from Monona County . `` And it 's that way across the state , with the wind , which ( can ) be very dangerous in ( fanning ) the fire . '' CNN 's Greg Morrison , Greg Botelho and Leslie Tripp contributed to this report .
NEW : A Fayette County official says fuel fires , fanned by strong winds , are a concern . Mapleton had been shut down as authorities probed a possible gas leak . The fire was reported at about 7 p.m. on Saturday in the town of New Market, located near the Kentucky border. Other Iowa communities are also hit hard by overnight twisters .