In a day he will never forget, a Chicago police sergeant saved one woman's life before getting down on one knee and changing another woman's life forever.

Mike Nowacki, a SWAT team sergeant and medic, was running in the Allstate Hot Chocolate 15K/5K charity race Sunday when a young woman collapsed near the finish line; her heart had stopped. The people crowded around her were yelling for a medic. Nowacki immediately sprung into action and administered CPR until emergency medical services arrived.

After the medical team took over, Nowacki finished the race and found his girlfriend Erin Gubala, a fellow Chicago police officer. He then got down on one knee and proposed. Gubala paused for a moment in disbelief before answering "yes."

"He's sweating and I wanted to talk to him about what happened down the way, find out more information, and then he got down on one knee and I thought that he was hurt and then he just said, 'Erin, I don't know what to say' and then I realized what was going on," Gubala recalled.

In a Facebook post about the events, the Chicago Police Department said the 19-year department veteran decided to run the race in full SWAT gear "for the love of his profession and commitment to excellence."

The woman who had collapsed was rushed to nearby Northwestern Memorial Hospital. There, doctors credited Nowacki's actions and the medical team's quick response for saving her life.

Police say the woman suffered a cardiac arrest and is expected to make a full recovery, according to a WLS-TV report.

If that's what a Sunday is like for Sgt. Nowacki, who can imagine what his Mondays are like?