He followed his sense of smell to the fire and was able to get the family out in time. 

Bay County Sheriff's Deputy Art Kleinert was patrolling in Auburn in the wee morning hours of Wednesday morning when he smelled smoke. He said that it was a different smell than just a fireplace, so he followed it...and saw smoke coming from a house.

He jumped a fence and pounded on the door with no response from anybody inside, so the Deputy kicked the door in and started yelling. He managed to get a man and a woman out of the house, with just the clothes on their backs - the smoke detectors went off AFTER he kicked the door in.

The fire chief says that it's likely that the sleeping couple would've been overcome by smoke if Kleinert hadn't alerted them to the fire. A true Michigan hero, indeed.