Hickory: In Baldur's Gate that would be impossible, if you mean literally *everybody*. Your level 1 character wouldn't stand a chance, without cheating.
Jonesy89: Not at level 1, no, but the mere thought of catharsis of being able to obliterate everyone after hitting the xp cap is making me consider trying to play just so I can send everyone to meet Minsc.
For additional sadistic fun, make sure you have the boots of speed, bow proficiency and all the detonation arrows you can carry ;)
It's funny that if you do that in Candlekeep, the guards won't come after you, but stealing that gem on the second floor of the inn is worth them chasing you and taking all the gold you're carrying. Maybe thats why the PC doesn't alert the guards after the assassination attempt, he/she knows the guards only care about borderline worthless gems. If the guards consider stealing a gem more serious than premeditated mayhem then they deserve a few arrows of detonation to the face. ;)