If you pull a fire alarm in any large U.S. city, it's likely that paid firefighters waiting at a nearby station will quickly respond. But seven out of 10 American firefighters are actually volunteers. They cover vast sections of the country, making up an aging network that is increasingly understaffed and overworked.
On a blazing hot day recently in western Kansas, two men have rushed from their jobs to douse a grass fire, for free.
"If somebody wasn't here to do it, this could get out of hand real quick," says Jason Lonnberg, with the Jetmore Volunteer Fire Department.