SHREVEPORT, La. (AP) - Several tornados toppled trees and utility poles and damaged numerous structures in northwest Louisiana Sunday night, authorities said.

Area television stations reported several injuries but none were immediately confirmed by Caddo Parish Sheriff's spokesman Edward Vailes.

"There are still a lot of areas we have not checked, but we've got major damage," Vailes said.

The storm knocked out power throughout the city, forcing law enforcement agencies to rely on backup power, Vailes said.

At least one of the funnel clouds touched down in the heart of the city, ripping up siding, shattering windows and scattering the broken glass.

"We've got lots of reports of broken glass downtown," Vailes said.

High winds also caused havoc on the roads, overturning an 18-wheeler and blowing recreational boats off trailers, Vailes said.