Rosie O'Donnell says people sometimes mistakenly think her new fiancee is her daughter. The 56-year-old television personality discussed Elizabeth Rooney, a police officer 23 years her junior, on Tuesday's episode of "Late Night with Seth Meyers" following their engagement. "[She's] a police officer in Worcester, Mass," O'Donnell told host Seth Meyers. "She is a mounted police officer -- she rides a horse. Yes, and she's 20 years younger than me." "It is sort of sad at the airport when people say, 'Oh my God. Is it you, Rosie O'Donnell?' 'Yes, it is.' 'And your daughter's so beautiful!'" she later said. O'Donnell said she saw Rooney's training as a police officer in action the first time she stayed the night at O'Donnell's home in Nyack, N.Y. "I had lived there for 20 years up in Nyack, and the alarm had never gone off, not one time. First night she stays there, the alarm goes off," the star recalled. "Before I'm even awake I hear [her gun cocking]. 'Stay right here! I'm going downstairs!'" "She, like, kicked in the kids' doors. She's, like, checking for someone," she said. "I was like, 'My God. This is like Cagney & Lacey.' You know? And then she comes upstairs, and she's like, 'Wait right here. I'm going to go talk to the cops outside there, sweetheart.'" O'Donnell, who got engaged to Rooney in October, said she appreciated her girlfriend's response. "You know, there's something so kind of warm and amazing to being with a woman -- as a gay person -- who has a lot of guy qualities," she said. "You know, she was in the Army for a bunch of years, and then she was a professional boxer. And she looks like a Barbie kind of." O'Donnell is actually parent to five children, including daughter Chelsea O'Donnell, who gave birth to her first child in December. O'Donnell said becoming a grandmother has been a beautiful experience.