A girl whose father was killed in the World Trade Center on 9/11 claims she was able to communicate with him and his coworkers after his death.
Lisa O'Brien said she would overhear her 4-year-old daughter, Jacie, carrying on conversations when there was no one else in the room.
"I'd find her talking to herself," Lisa told ABC News. "And I'd say, 'Jacie, who are you talking to?' 'My dad. Talking to daddy.'"
Jacie would then claim to be talking to her father's coworkers -- or "the boys," as she put it.
"She named the guys that she had never met before," Lisa said. "I showed her a picture and said, 'Do you know who these guys are?' And she said 'Oh mommy, those are the boys.'"
At the age of 13, Jacie spoke to ABC News and recalled her experiences.
"They'd be telling me knock-knock jokes, and I was just talking to them," she said.
When asked how she reacted to her daughter's claims, Lisa said she felt jealousy.
"I was jealous," she admitted. "Because she got to see them and I didn't.
The O'Briens are not the only people who say they've had supernatural experiences related to the events of 9/11.
Monica Iken, whose husband, Michael, was killed on 9/11, says she woke up one night to find her late husband standing at the foot of the bed.
"He was all glowing, and I just sat up, I said, 'Thank you for coming,'" Monica recalled to ABC News. "As quick as I said that, he left. But he was smiling. He was telling me he was there with me. It was not a dream. He was literally standing there."
Dr. Katherine Shear, a psychiatrist at Columbia University, said that while such episodes are common among people who have lost a loved one, it is impossible to explain them entirely.
"These kinds of things tend to happen with people when people lose someone very, very close to them," Shear said. "Obviously, there's so many things that we just do not understand."
Lisa and Jacie's story went viral after Little Things featured it on Facebook Nov. 1. It has already been liked over 2,000 times.