An expectant mother would be sharing, and possibly learning for herself, the gender of her unborn child.
That's when terror came in.
Police near Cincinnati say two gunmen in hoodies opened fire with handguns, killing a woman and wounded eight others, including three children.
Now, instead of celebrating new life, the group will be mourning a loss and caring for the injured.
Autum Garrett, 22, who authorities believe is from Huntington, Indiana, was pronounced dead at the scene.
The eight other victims, including an 8-year-old, 6-year-old and 2-year-old, suffered non-life threatening injuries, police said.
The injured were taken to Cincinnati Children's Hospital Medical Center and University of Cincinnati Medical Center, authorities said. Colerain Township, Ohio, is about nine miles northwest of Cincinnati.
The suspects remain unknown and at large.
"We don't know who the suspects are or why they did this," said Mark Denney, chief of police in Colerain Township, on Sunday evening. "We're not sure if (the suspects) were allowed in or they forced entry at this point."
A gender reveal party often involves the expectant parents and their gathered guests learning the soon-to-arrive baby's gender at the same time. It includes a dramatic moment when pink or blue is revealed to all gathered -- by opening a box that's full of balloons in one of the colors, for instance, or slicing a cake to reveal blue or pink coloring inside.
A family member told CNN affiliate WLWT
that a pregnant woman was shot in the leg and lost her baby. The woman has been treated and released from the hospital, the station reported. Denney couldn't confirm that detail. It was not clear whether she was the guest of honor.
Police also didn't know how many people were in the home for the party or the possible relationship between the suspect and the victims, Denney said.
James Love, spokesman for the Colerain Township Police Department, told HLN's Erica Hill Monday that investigators are following every lead they get. "This situation seems to have come out of the blue," Love said.
"We as police and the community has been recently coming together, trying to unite ourselves, trying to create a community sense, once again trying to put up good defenses," he said. "Lights, cameras and everything else to try to cut down on what has become a problem in this neighborhood."
Love said he wouldn't call the neighborhood crime-ridden, "but it is an area that we do focus on."
The group had just started to watch the movie when the violence began, the Cincinnati Enquirer reported.
In 911 calls from the incident obtained by CNN affiliate WCPO
, witnesses sound panicked and confused as to what has happened.
"There's a whole lot of people here are shot," one man tells the operator, as people scream in the background.
"I just seen two people walk by, I looked outside, next thing I know they just ran in and just start shooting," the man says. He tells the operator he thinks he has been shot in the stomach and that he's bleeding.
Another woman calls 911 from outside the house.
"There is little kids hurt and everything," she says. "I was sitting in my car, they just ran in and started shooting. There's a pregnant girl here ... oh my God."
At the request of the operator the woman yells at people in the house to find out how many people have been shot, but is unable to establish the number. She says she saw the gunmen run away.
One caller says, "We were having a baby shower, like a reveal party."
A neighbor calls emergency services, but cannot provide details of the injured.
"Ma'am, all I know is, I don't know what's going on, all I know is she's a neighbor. I was at home minding my business and I just heard someone in distress banging on my door and a young lady was bleeding and she said she'd been shot and so had someone else and I just tried to come out and see what was going on," she says.
'It was horrific'
Candice Verga, a family friend who attended the party, told WLWT
it was "positive" and "happy." All of that changed when she heard the gunshots.
"Everybody's screaming and crying and it's just all panic and I'm even shaking and everything," Verga said.
Neighbor Cheyenne Sizemore heard what sounded like six to seven gunshots, according to WLWT.
"It was a pretty quick succession, it was one after the other, like they went in there and they unloaded as many bullets as they possibly could and then ran off," Sizemore said.
Officers were dispatched to a call of shots fired about 11:21 p.m., police said.
One responding officer said "it was horrific, something that was unimaginable," Love said.
Denney urged residents to take the same reasonable precautions they always do, including calling police if they see something suspicious and locking their doors.
"But we have no information that makes us believe there is any specific threat to our community," the police chief said.
"Our hearts are heavy with what we've seen and experienced in our community," Love said.