Ned Peppers would not close for another hour, and the crowd inside the bar and on the outdoor patio early Sunday morning was lively. The line to get inside stretched around the block, and the revelers were black and white, men and women, spanning at least two generations. One was the mother of a newborn, another was a nutrition trainer. Within seconds, both would be dead, along with seven others.

Among the victims killed in the barrage of gunfire outside Ned Peppers, a popular spot in Dayton, Ohio, was the gunman’s sister, a 22-year-old college student described as “bubbly” and “outgoing.” Investigators had not determined on Sunday evening whether the gunman, armed with a military-style rifle and clad in protective armor, had specifically targeted his sister or anyone else in the crowd.

[Update: Dayton gunman had history of threatening women.]

The gunman, identified as Connor Betts, 24, was killed by the police as he tried to run into the bar, located in an area of Dayton known for its night life, popular with college students and heavily policed. His sister, Megan Betts, graduated from Bellbrook High School two years behind her brother, and played in the marching band with him. She was “outgoing,” while her brother was more withdrawn, said Alex Gerbic, another member of the band.

“She was a very bubbly personality — very kind,” Mr. Gerbic said. “From what I knew, they were close, as brother and sister. This was five or six years ago.”