CHICAGO (CBS) — The lives of three complete strangers collided at a hot chocolate race over the weekend.

And in the end, one woman’s life was saved.

CBS 2’s Jim Williams met with the heroes.

Among the thousands running the 15/5K Hot Chocolate race Sunday, two public servants: Merrillville, Indiana Fire Department Captain

Walter Cook and Chicago police Sergeant Mike Nowacki.

“I guess to make it a little more challenging, I decided to wear my full SWAT outfit,” Nowacki said.

Fifty pounds of his SWAT gear and one lighter, but priceless posession: an engagement ring he planned to present at the end of the race to Officer Erin Gubala, on bike patrol that morning.

“I had the ring in my pocket, in my cargo pocket, “Nowacki said.

But that would have to wait.

Cook and Nowacki saved a life of another runner. They were close to the finish line, no more than about 200 feet away, when they saw their fellow runner collapse.

They stopped their run and went to her aid.

“She’s not getting up,” noted Cook.

Nowacki added “as a police officer we go to the sound of gunfire and as a SWAT medic, we also have that instinct to go toward the sound of someone calling for a medic.”

The young woman was in cardiac arrest. Cook and Nowacki, until then strangers, both did CPR.

“Her heart stopped. So we didn’t have a pulse,” Cook said.

“We began doing chest compressions,” added Nowacki.

The young woman was revived and rushed to Northwestern Memorial Hospital. Cook and Nowacki finished the race. Nowacki popped the big question:

“He got down on one knee and I thought he was hurt,” said Gubala.

“She had to say yes then after that,” laughed Nowacki.

Captain Cook, who visted the young woman in the hospital, said many runners wanted to help.

“It’s a wonderful world, I’m telling you,” said Cook.

A big run, a life saved and an engagement.

The young woman is still in the hospital but is expected to be OK.