CHICAGO (AP) — The National Weather Service says a tornado outbreak in the Chicago area this week produced at least 11 twisters.

Preliminary findings show they were relatively weak.

No injuries were reported when Wednesday’s storms ripped roofs from buildings and toppled trees in the Chicago area and points west.

One tornado touched down near O’Hare International Airport.

The weather service said Friday that at least eight tornadoes had preliminary ratings of EF-0.

Those produce winds as high as 85 miles per hour.

The three others had preliminary ratings of EF-1.

They pack winds as high as 110 miles per hour.