Kill Or Be Killed

~Peeu! Peeu! Peeu! 

Wally, Cambridge and their gangs began taking care of as many enemies as they could, shocking Armstrong and the rest. 

Lying trough. What the hell was going on here?

A wave of dismay clouded their hearts while trying to make heads or tails of the situation.

For one, do you know the distance between them and these intruders? The only thing that can make such a shot should be an arrow or a spear with ample weight and enough considerations to make it go the distance.

Moreover, they were up on a tree, mind you... So even if one shot a spear from where these intruders stood, it was indeed a challenging feat to keep the spear this high up. 

The spear's arc should go like a half-circle (semi-circle). It goes up and then descends after a while. So what sort of superhuman strength would allow such an attack this high up in the towering trees?