Firefighters reveal some of the most terrifying - and rewarding - moments on the job

• Photographer Paul Mobley documented almost 50 fire houses across America.
• Mobley and writer JoEllen Kelly gathered firefighters moving stories about what brought them into this line of work.
• The new book "American Firefighter" documents their stories and portraits.

When photographer Paul Mobley set out to document almost 50 fire houses across America, he had no idea what the life of a firefighter entailed.

By the end of his project, he had a newfound and immense respect for the men and women who serve in the field everyday. Mobley and writer JoEllen Kelly created a collection of moving photographs paired alongside each subject's personal story for the new book "American Firefighter."

"These courageous men and women experience the highs and lows of life on a daily basis and sometimes witness things the rest of us couldn't possibly imagine," Mobley wrote in his afterword in the book.

"From the first man we photographed in Missouri - Captain Mario Montero, who broke his back jumping from the third story of a house during a fire - I knew this was going to be a trip like no other," he wrote.

The fire houses welcomed Mobley with open arms, offering food and gifts as a thank you for documenting their work and hearing their stories. "These are the kinds of people I truly admire, the kinds of people I wish I could be around every day," wrote Mobley.

Ahead, a sample of portraits from "American Firefighter" and excerpts from their powerful stories.