Despite the smell in Sterling and Rock Falls on Monday, there’s no widespread natural gas leak, officials say.

The smell, which prompted many area residents to call 911, is a result of a mercaptan leak that Nicor Gas construction crews ran into while decommissioning its former site off McNeil Road between Dixon Avenue and Route 30 in Rock Falls. No natural gas was involved in the leak, Rock Falls Fire Chief Ken Wolf told Shaw Local.

Mercaptan is an odorant added to natural gas that gives it its distinctive rotten egg smell so that the odorless and colorless gas can be detected in case of a leak.

The odorant leak stemmed from an abandoned line and tank at the site. Nicor’s construction crews have since stopped the leak and are going to bring in crews to clean up the remaining product, Wolf said.

Those who are “concerned about the odor of gas in their house, they can still contact Nicor and they can still contact the fire department. We will come out and verify either the presence or the lack of a presence of a hazard,” Wolf said.

The city of Sterling posted a statement about the smell on its Facebook page, which says, “if you believe you have a gas leak at your home or business, please continue to call 911. However, due to multiple odor-related calls in the area, response times may be slightly delayed.”

Rock Falls officials are waiting on a statement from Nicor regarding the incident, but have not received it yet, Wolf said.