One witness told local media: “He [the gunman] was a kid, about 17-18 years old. Suddenly, he walked through the front door (of the school yard). As soon as he entered, he pulled out a gun. It was a long, stocky one, like one of those pump-action shotguns with rims.”
Source: https://www.bbc.com/news/articles/c2k33xk24nyo?at_medium=RSS&at_campaign=rss