MOUNTAIN VIEW (CBS SF) — Five people were hospitalized Thursday after a hazardous materials response to a robotics company in Mountain View, fire department officials said.

Firefighters received a call at 12:41 p.m. reporting an odor from a car making people sick. They responded and found people reporting feeling ill at two locations operated by the company Nuro at 1300 Terra Bella Ave. and nearby at 1340 W. Middlefield Road.

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Witnesses and patients reported that a Toyota Prius was being charged in an enclosed space at the West Middlefield Road address when people said an odor was coming from the Prius’ battery.

The smell was first reported to Nuro management at about 10:30 a.m. and the building was evacuated, the Prius was unplugged and the battery was removed from the vehicle, fire officials said.

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The building was declared safe by management for re-entry after lunch, but some people reported symptoms of illness at about 12:30 p.m. and the fire department was called shortly afterward.

The fire department’s hazardous materials team conducted tests but quickly determined the building was safe for occupancy. Nevertheless, five Nuro employees were taken to hospitals while four others were evaluated but refused further care, fire officials said.

Mountain View fire spokesman Robert Maitland said crews could not determine what might have prompted the employees to feel ill.

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Officials at Nuro later said the Prius’s battery overheated, creating the smell.