Aubrey Peters, 16, of Noblesville was fatally wounded about 11:20 p.m. Sunday and Jacob Travis McDaniel, 20, also of Noblesville was charged with reckless homicide and pointing a firearm Monday in Hamilton County Superior Court, the Indianapolis Star reported.
Bail for McDaniel was set at $15,000 and he has a pretrial hearing set for Feb. 21.
An affidavit states McDaniel was showing Peters and two men a shotgun and a handgun. One of the men told investigators McDaniel tried to get Peters to hold the handgun, "but she didn't want to."
Williams told police McDaniel then ejected the magazine from the gun, pointed the weapon at the teen, took the safety off and pulled the trigger, firing a bullet, the newspaper said.
"Aubrey clutched her chest and said, 'What just happened?'" the affidavit stated.
Efforts to revive her at the scene and at a hospital failed.
Williams allegedly concocted a story for the men to tell police.
"McDaniel then stated, 'The story is the gun fell off the table and went off,'" the affidavit said.
Peters had been given an award for helping save two young sisters who fell through the ice on Morse Reservoir. A seventh-grader at the time, she ran into her home to alert her grandmother and called 911 on her cellphone as she headed back to the shoreline, the Star said.
Peters was an excellent student and was artistic, Noblesville High School Principal Jeff Bryant said.
"We're a large school, a large community. We have tragedies," Bryant said. "I don't know that I've seen one that has affected as many people as this one has -- both adults and students.
"It was a tough day today, Aubrey was well-liked. She had a huge smile that she shared with a lot of her classmates. She had a bright future ahead of her. When this sort of thing happens, it hits a lot of people.
"It hurts your heart."
In another weekend shooting in the Indianapolis area, a 3-year-old boy was killed when he pulled a loaded gun off a kitchen counter and shot himself in the head, Indianapolis police said.
No charges had been filed in that case, the newspaper said.