Tim Bergon took the photo to send to his wife, so that she could know he was alive and kicking after he attended the scene of a wildfire in San Diego.
'When you see how exhausted they are, it just makes you really, really grateful for all that they do, and all they always do'
He sports a cheesy grin into the camera, as his colleagues can be seen in the background, resting on the ground following their ordeal.
And after Plan 9 Alehouse, who are friends with the Bergon family, posted the picture to their Facebook page, the picture quickly spread across the internet, receiving thousands of likes.
The restaurant captioned the picture 'Thank you!!!' with hundreds of Facebook users then responding to show their gratitude.
The owner, Monica Calles, commented: 'When you see how exhausted they are, it just makes you really, really grateful for all that they do, and all they always do.'
As a thank you to the men, Plan 9 has now set up a Firefighter's tab on their Facebook page - so that people can virtually 'buy them a beer.'
Fires raged across the region last week, with 5,000 firefighters on standby in the state.
California has been experiencing a terrible drought in recent weeks, and residents have been told to prepare for a long wildfire season this year.