In my country we have wild boars and this behavior is not uncommon. Most of them are with injured animals trying to escape by a direct charge of the perceived danger.
It is also happening with saws that are defending piglets.
To me, it happened three times, all of them during driven hunts. At first, I was just an underage beater and the only thing I was allowed to carry for defense was an axe or a strong stick. The first time I was saved by a dog that made contact with the boar and changed his direction. The second time I was able to climb in a tree fast enough ( I'm still amazed how fast I was back then). The third time I wounded a large female and, while recovering her, she attacked me ignoring dogs and everything. I managed to shot her at about 5m from me...