Seminole, FL – A car left running in an apartment garage sent four people to the hospital and forced the ventilation of 40 apartments Sunday morning.

Seminole Fire Chief Heather Burford said Carbon Monoxide from the vehicle sent four people to the hospital for observation. Burford said firefighters were forced to open the windows and doors to the other 40 apartments in the building affected.

A resident called the fire department when she smelled something different and thought something was wrong, Burford said.

Firefighters forced open three garages before they found the vehicle that caused the odor, according to Burford. CO2 is an odorless gas, but the smell of the engine vehicle alerted the resident.