MODESTO, Calif. (KTXL) — Some nearby residents were told to stay inside Monday as a sulfur fire burned inside a Modesto farm supply warehouse.

The Modesto Fire Department said fertilizer-grade sulfur was smoldering inside the Stanislaus Farm Supply warehouse.

Modesto Fire Chief Darin Jesberg told FOX40 there are about 900 tons of sulfur in the warehouse. At this point, they do now know how much of that is smoldering, he continued.

While there were no threats to the 40,000-square-foot concrete warehouse, the Stanislaus County Office of Emergency Services told residents who live within a 1-mile radius of 624 East Service Road to shelter in place.

Stanislaus County OES officials asked that neighbors close their doors and windows and turn off their heating, ventilation and air conditioning systems due to the potentially hazardous air outside.

County officials did not say when residents would be able to leave their homes.

First responders from Modesto, Ceres and the county, as well as the Department of Environmental Resources, have been working to isolate the sulfur product in the warehouse.

This story is developing. Check back for updates.