PETALUMA (CBS SF) — Employees were evacuated from a Target store in Petaluma Wednesday morning because of a sulfur-type odor, a fire captain said.

Firefighters responded around 9:50 a.m. to a report of an employee having a medical problem at the store at 401 Kenilworth Drive, Petaluma fire Capt. and Acting Battalion Chief Jude Prokop said.

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Additional ambulances and fire personnel responded after a 911 dispatcher was told there was a sulfur-type odor in a storage room and more employees needed assistance, Prokop said.

Fire crews evacuated the store and set up a field treatment area for patients. The store was closed while fire crews investigated the cause of the smell, Prokop said.

The odor was traced to a janitorial area in the rear storage area and the fire department’s hazardous materials team checked the area with gas monitors.

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The odor was found to be coming from a malfunctioning sewer drain, Prokop said.

No toxic or harmful gases or public safety hazards were found, he said.

The fire department’s medical team evaluated 40 employees. Four patients were treated and released at the scene, Prokop said.

The store manager arranged to repair the sewer drain and the store was ventilated and reopened.

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