At least two people were shot, one fatally, following a graduation ceremony at an alternative learning high school south of Atlanta on Friday, police said.

An argument preceded gunfire after attendees of the 6 p.m. event at the Perry Learning Center's performing arts venue in Clayton County, Georgia, exited to an overflow campus parking lot, school police chief Thomas Trawick Jr. told reporters.

NBC News affiliate WXIA in Atlanta reported that the deceased was a woman in her 40s who was shot three times in the chest. A 21-year-old was shot in the leg, according to the station. A pregnant woman was apparently also injured by the subsequent rush to flee.

It's not clear what sparked the confrontation. Trawick said the search for whomever opened fire was ongoing.

The attack lit up social media because it took place the same day a 17-year-old student in a trenchcoat barged into a Texas high school classroom and opened fire, killing at least 10, police said. They identified that suspect as Dimitrios Pagourtzis.

When a reporter asked Trawick how he felt when he got a call that there was a shooting on school property, he said, “I was pretty emotional because the last thing you want to do is have a situation at a graduation that results in anyone being injured, and definitely not being shot.”