Minutes later, he realized they weren't going to make it. He left his wife to call 911, and when he returned, she had delivered their second child, a little girl they've named Ariana.
Catherine says it was only when she got to the hospital that she realized it was Mother's Day.
"It's already amazing to give birth, but this is the most amazing present that I could have ever gotten on Mother's Day," she said.
"I just couldn't believe my eyes that the baby was there and actually in her arms already. And I just couldn't believe you could have a baby in four minutes," said father Alan Harris.
Ariana weighs 6 lbs. 12 oz. She has a 2-year-old brother named A.J.
The entire family is doing well.