Once on scene, first responders immediately detected very high levels of carbon monoxide and removed everyone from the store.

Since then, they’ve placed fans throughout the store in an attempt to ventilate but the carbon monoxide levels remain high.

All of the 13 people treated were Walmart employees.

The seven who were hospitalized were taken only out of an abundance of caution, according to Orange County Fire-Rescue.

The source of the leak was traced to equipment that was being used to remodel the store.

Fire officials say they’ll remain at the store and keep the evacuation in place until their meters show acceptable levels of carbon monoxide.