A mercaptan leak coming from the area of 1100 Umatilla Street in Denver is causing an odor in parts of the city.

Mercaptan, a harmless gas, is often added to natural gas to give it a rotten egg-like smell.

Denver Fire says the winds are blowing the odor north.

The Denver Fire Department and Xcel are working to stop the leak. Anyone with a concern should contact Xcel.