A storm system that brought rain, hail and strong winds to several Midwestern states spawned tornadoes Thursday night in parts of Nebraska.

A few businesses sustained severe damage and at least one house was partially destroyed when a tornado struck the southern outskirts of Aurora.

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Tornadoes were also reported in Kearney, where about 90 rail cars were derailed outside the city limits.

There was no immediate report of injuries.

Gov. Dave Heineman declared a state of emergency Thursday night, which allows access to state and federal resources for storm cleanup. He readied the Nebraska National Guard in case its help was needed.

"We won't know the full extent of the damage until tomorrow. However, it appears that Kearney was hardest hit and that is where our assistance will be focused overnight," Heineman said late Thursday.

Initial reports from the Nebraska Emergency Management Agency indicated several dozen homes were damaged in both Aurora and Kearney. Heineman planned to travel to those areas Friday.

Heineman's spokeswoman, Jen Rae Hein, said the state's emergency operations center was set up Thursday evening. A second post was going to be established closer to the affected communities.

State officials closed down Interstate 80 from Aurora to York just before 8 p.m. because of downed power lines.

The heart of Aurora appeared mostly untouched by the storm, but twisted trees and metal buildings in the south were telltale signs of a tornado.

Farther west, there were reports of downed trees and power lines throughout Kearney, as well as reports of damage on the University of Nebraska at Kearney campus and at the county fairgrounds.

The Buffalo County emergency manager asked all Kearney residents to remain at home Thursday evening. Travel was discouraged because of storm damage in parts of the city.

Nebraska Public Power District spokesman Mark Becker said transmission lines were down from Kearney to the towns of Elm Creek, Tower and Riverdale.

He said 12,000 customers were without power in Kearney Thursday night, and crews were working to fix lines in the northwest, northeast and southeast parts of the city. Crews got a late start on repairs because the utility had been waiting for a second wave of bad weather to pass.

The National Weather Service issued several advisories for Nebraska and Kansas into Friday morning, including flooding warnings for areas already struggling from heavy rains earlier in the week. That storm system dumped 7 inches of rain on some parts of central Nebraska.