Guild Wars 2

Hey, I’m a thief and right now, at least I think the story instance “Thieving from Thieves” is broken, The one where you light all the bombs on fire. I didn’t really kill anything, just stealthed through the entire thing, and lit all the bombs, but then nothing happened after that.
Just wondering if I’m missing something, but I think it’s a bug.

http://wiki.guildwars2.com/wiki/Thieving_from_Thieves

“Create diversions by detonating some of the powder.

Though not stated, it appears you must kill all centaurs in the camp to continue the story, otherwise the last objective will not appear "