Four people, including three police officers, were hospitalized after being exposed to a toxic substance in a vehicle parked outside a Dartmouth, N.S., grocery store.

Halifax Regional Police say they got a call at 4:46 p.m. Thursday about a woman suffering from a medical emergency in the 500 block of Portland Street, behind the Sobeys store.

Officers found the woman inside the vehicle, and as they tried to help her, they were exposed to a chemical substance.

All four were taken to hospital. Police said in a release around 11 p.m. that the three officers had been released, while the woman was being treated for injuries described as non-life threatening.

Halifax Regional Fire and Emergency district Chief Brad Connors said two materials in the car mixed together to create hydrogen sulfide, a gas that is hazardous to anyone who breathes it in.

In small concentrations, the gas smells like rotten eggs, but is odourless in higher concentrations because people lose their ability to smell the gas.

Fire crews wore hazmat suits

Just before 7 p.m., fire crews were donning hazmat suits to enter the car and contain the material. Connors said an environmental company would then be called in to remove the substance.

The vehicle was far enough away from nearby buildings that it did not pose a danger to the public, he said.

Police said in the release later in the evening that the incident had been resolved.

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