What could cause an explosion big enough to wipe out a hamlet?

I've got this nifty map that I downloaded from the Dungeon magazine archives. It is a picture of a town that has been completely wiped out. Toward the end of the last game session, the party, who were spending the night in a hamlet in the middle of the plains, were awakened by a bright flash of light that was followed by a rumbling explosion. (Yeah, I know. I painted myself into a corner.) They have a map of the region, and the destroyed town is about two or three days walk from their present location, if they push straight through. Of course, they aren't sure exactly where the explosion came from, only the direction.

So, when they get there, what should they find?

I should perhaps mention that the immediate region also contains a keep of a self-styled knight protector and his men, three other agricultural hamlets and a ruin to the north. The east side of the region is bordered by forest, which is where the party was originally headed.

Edit: tried to post the map, but failed.

Ok, here's the map.

Hmm-

1) An epic delay-blast fireball/hellball.

Why? Perhaps the caster saw into the future and saw someone who will kill him had their anger originate from that village- so, just kill everyone.

They would find the burnt bodies of a lot of people in bed- and perhaps some of the wood is still magically lit.

2) A portal opening that got out of control.

A cleric of the town was attempting some new prayers that would open a permanent portal to the plane of positive energy- he had hoped it would able to cure all of life's ailments, but it got out of control and exploded.

The area could be infused with the energy- causing spells cast with the [good] marking to be cast as if on the positive plane.

They would not find people- they have become the positive energy equivilant of shadows.

3) A meteor crashed- and it was carrying something not very nice.

A Witchlight Marauder might be fun, or you could go the Superman 2 route- and have a mighty villian released that was imprisoned in the stellar rock.

They find something they don't want to deal with- and run off to the knight-protector for help.

4) A dragon attack

The town had been secretly serving a dragon - kidnapping people passing through and feeding them to the serpent. An enemy dragon came through and wiped out the supplicants.

Similar to #1, but some random BIG claw marks in the ground.

5) Hellish Sacrifice

The knight protector sold their souls in exchange for immortality/power/lifetime supply of pizza/whatever.

They would find the destroyed area, but no bodies. Some low level imps and other demons lurking about (they escaped during the ceremony).

Hmm, that is all I got at the moment.

FD

what about: a fire spred through town, the explosion the PCs witnessed was when it hit the local alchemy lab (which exploded with such force, it blew the fire(s) out...?

two words: Stupid gnomes

three words : evil stupid gnome

A wild surge or a zone of wild magic.
A evil mage try to scare the villager zig insted of zag.

Fireworks -- It was almost the Festival of a Thousand Stars, and we'd be damned if we weren't going to make the Thunderlord proud with our display. O'course, we oughtn't've let those Penksy boys guard the sheds -- they never could keep off thier damn pipeweed, not even for a minute.

Explosives -- Aye, the gnomish lad had sold us true. We'd be able to use his "thundersticks" to seal every entryway to the old mine, trap those bastard greenskins to stew i' thier own blood. They must've heard us, what with our revelry the night before we planned to take thier battle to them, for someone -- or somethings -- stole i' the storehouse an' had the box half-way through the village, when up went the hue an' cry. The bastards must've dropped the crate -- an' son, let me tell you, you never drop a crate o'thundersticks.

Magic Ward -- The cover was writ with "Infernomicon" -- how in blazes was I to know what the opening would entail? Blasted bloody wizards and their blasted bloody books!

Retributive Strike -- Ol' man Witherstone said he'd rather break his lucky walkin' stick than let the revnoo take it fer tithe, an' rot their greedy eyes to hell. Well, hell's what he got.

-- Nifft

Yep, them dern gnomes. Always blowin up the nuclear power plants.

How about something slightly futureistic? (ever since i saw the Sleeping Imperium firearms rules, I just haven't been satisfeid with medieval.)

Like, nuclear explosion? Perhaps them dern gnomes built a nuke plant, but didn't have enough trained workers? this could be cool if there was, say, the underground levels of the plant still intact a few miles away with a bunch of mutants. The characters could find this by tracing the circumference of the blast and then going to the center.

Or maybe the death of a god or destruction of a conterminous plain?

portable hole in a bag of holding?

How about the Tunika<sp> blast in siberia? all sort of stuff on that.

I like a plane of some sort; postive.negative,shadow opening there and a rift causes the explosion. All that is left is the village destroyed. Perhaps the party can travel to this plane over the next few days and see a exact image of the town complete with the real people not knowing they are no longer on the PM. Or perhaps they do....