Pettigrew the murderer?

[magicroxx]

No: HPFGUIDX 75855

Something has been bothering me since POA and that is if Peter was 
supposed was supposed to be such a weak wizard, then how did he blast 
half the street away and kill all those people? I don't see how this 
could have happened. I don't have the books with me because I am at 
work. Also, he just cuts his finger off, blasts the street apart and 
then tranforms into a rat and runs away. He was so squimish about 
cutting his hand off that I think Sirius would have realized what he 
was going to do and have been able to stop him. 

At first I thought maybe Voldemort could have been possessing him, 
but he was a little.....under the weather at that moment. Could there 
have been someone else there?

Roxx