What curse did Peter Pettigrew use to kill thirteen Muggles at once?
Harry lay listening to the muffled shouting next door and wondered why he didn’t feel more scared. Sirius Black had murdered thirteen people with one curse; Mr and Mrs Weasley obviously thought Harry would be panic-stricken if he knew the truth. But Harry happened to agree whole-heartedly with Mrs Weasley that the safest place on earth was wherever Albus Dumbledore happened to be.
Prisoner of Azkaban - page 55 - Bloomsbury - chapter 4, The Leaky Cauldron
I believe Avada Kedavra has to hit a person directly to kill them, yes? I can't think of any instance in canon where Avada Kedavra, for example, ricocheted and killed more than one person in one instance (Avada Kedavra ricocheting off the statues in the Ministry of Magic doesn't count!).
So what curse did Peter Pettigrew use that would have killed thirteen Muggles in one shot?
Is there a canon spell that could possibly cause such extensive damage and death?
A canon-based answer would be great.