A bad odor that has settled in a large area of the city is making some people sick to their stomachs.

The Fond du Lac Dispatch Center received calls from businesses and homeowners beginning around 9:45 a.m. Friday.

"It's pretty much a mystery," said Lt. Joe Maramonte of the Fond du Lac Fire Department.

Calls started coming from the areas around Lenz Truck, Fleet Farm and then Holiday Dodge and a Fond du Lac County Airport hangar.

A crew checked an Alliant station across from Fleet Farm that injects odor into natural gas and determined that it was not the cause of the foul stench.

"We are now thinking it might be from the old landfill on Rolling Meadows Drive," Maramonte said around 11:30 a.m., adding that the odor seems to be all over the city.

The odor has been described as "rotten-egg sulfur."

The wind was out of the south-southwest, so the odor couldn't be blamed on Kaukauna paper mills.