For a time, their escape seemed flawless. The current was strong and they were moving at a good pace. Unfortunately, that was not to last. 
The dwarves all crashed into the closed gate, one by one their barrels built up into a small traffic jam of sorts. Thorin cursed their misfortune, making an effort to open the doors himself. “No!”

A few of the elven guards drew their swords, but one was suddenly shot in the back with a black arrow. Several growling orcs swarmed over the guard post, killing the elves nearest to them. Multitudes of orcs ran in from the bushes, Bolg among them. With a nasty sneer, he looked to his army. “Gorid! Zib! Goridug! (Slay them all!)"

Two orcs shot at Saeril, and the rest went for the company. Bilbo managed to kill one orc with Sting, and Dwalin elbowed another in the face. 
Amidst the chaos, Kili looked up and saw the lever the guard had pulled earlier. This may have been their only chance.
Quickly, he scrambled to get out of his barrel and ran up the stairs towards the lever. Without a weapon, he could only duck as a sword was swung at him.

Dwalin knew this would not play out well. Using strength alone, he managed to rip a sword away from one of the orcs and tossed it to Thorin's nephew. “[i]Kili![/i]”
Kili caught the weapon and spun to pierce the orc as another leaped up from behind him, raising its spear to stab him.  
Several yards away, Bolg had Kili in his sights. Without hesitation, he took aim with his bow. Just as the youngest Durin reached for the lever, Bolg fired an arrow and hit Kili in the leg.

Kili froze in place, his eyes wide in shock. Though he had grown up learning archery, he'd never been hit with an arrow before. The pain was incredible, and he nearly fell over from the force of it. Groaning, he strained to pull the lever, but could not make it and collapsed to the ground. Without mercy, Bolg nocked another arrow to put the youngest out of his misery.