VIDEO: Tornadoes rip through Iowa

MARSHALLTOWN, Iowa -- A tornado hit the city of Marshalltown on Thursday, the Iowa Department of Homeland Security and Emergency Management said.

There were no immediate reports of injuries, the agency said, but there were reports of several tornadoes in the area, about an hour northeast of Des Moines.

Marshalltown officials declared a state of emergency, said City Administrator Jessica Kinser.

"Everyone is advised to stay away from downtown Marshalltown until further notice," she said in a statement. "We also ask that people stay off cell lines unless necessary, to allow for emergency phone traffic."

About 27,000 people live in the town. Many of them were without power; Alliant Energy reported 6,690 homes and businesses were without electricity.

According to CNN affiliate WOI, another tornado damaged houses in Bondurant, about 10 miles from Des Moines.

The storm knocked out power and telephone service at city hall, officials said.

Police say people have been taken to a local hospital after a tornado hit a factory in Pella where some people were working.

Pella Police Lt. Shane Cox told KCCI-TV some people from Vermeer Manufacturing were taken to a hospital, but he didn't know the extent of injuries or the number of people.

He says emergency responders are attempting to get inside the damaged building to see if anyone is trapped inside.

One of the factory's several manufacturing buildings sustained extensive damage with metal strewn across the parking lot and across the street into a cornfield. Vehicles were overturned and piled onto others.