Faced with the sudden change in their circumstances, the two boys remained calm and engaged the wild boars in battle. They wanted to end it as soon as they could in order to prevent anyone from taking advantage of them.
William didn't bother to sneak attack the two boys, because he wanted to find a safe place to make his base. He was not in a hurry to collect points, since it was only the first day. What he prioritized first was his safety.
When William left the scene, two arrows came flying from somewhere in the forest and struck the backs of the two boys who were busy dealing with the wild boars. Although they had already heightened their senses, in order to escape being ambushed, the two arrows still managed to avoid their detection.
The two boars didn't miss this opportunity and continued to charge at the two wounded boys. The impact of their charge sent the two boys rolling across the ground which aggravated the injuries they had received from the arrow.