Good ways to RAW to start an Undeadpocalypse in E6?

[danzibr]

Party will begin, level 1, doing normal life stuff in a normal mid fantasy world. Then bam, undead apocalypse. It'll be a lot of survival horror, and they'll grow stronger, discover the main plot (I'm thinking a Nightwalker is behind it all, who'll be the BBEG). Ultimately they'll discover the world it screwed and they'll Travel Through Time to save the day. Maybe it'll still happen anyway, still up in the air.
At some point, probably over the summer, I'll be DMing for my family over Skype. We have an old campaign, but I want to ditch it in favor of what's in the title. I perused the SRD and found the following
Undead capable of creating spawn in a short amount of time
Shadow/Greater Shadow: http://www.d20srd.org/srd/monsters/shadow.htm
Wraith/Dread Wraith: http://www.d20srd.org/srd/monsters/wraith.htm
Spectre: http://www.d20srd.org/srd/monsters/spectre.htm
Shadow of the Void: http://www.d20srd.org/srd/epic/monsters/shadowOfTheVoid.htm

Undead capable of creating spawn but not in a short amount of time
Ghoul/Ghast: http://www.d20srd.org/srd/monsters/ghoul.htm
Mohrg: http://www.d20srd.org/srd/monsters/mohrg.htm
Bodak: http://www.d20srd.org/srd/monsters/bodak.htm
Vampire: http://www.d20srd.org/srd/monsters/vampire.htm

I have a problem though. I noticed all the undead (unless I just overlooked stuff) capable of creating undead quickly are all incorporeal. The party will be starting at level 1, so uhh, that's a bit of a problem. Oh, and they make incorporeal undead.

So I could use some corporeal undead which make more corporeal undead, but it wouldn't have a very hectic feel to it, methinks. What's worse, they're quite strong for a low-level party.

Here is my main question: Are there any weak undead which rapidly make more undead? I'm thinking like Resident Evil movies. Some special type of Zombie, perhaps?

I know I could just homebrew this, but I'm really interested to see if RAW treats this anywhere.

Here is my second question: Anyone play/run such a campaign? How'd it go?

EDIT: Oh, another reason I want E6 is because I don't want anyone to be like, ``But why didn't Elminster just stop it?'' And I prefer low levels of gameplay. And it fits well with survival horror.

ANOTHER EDIT: The base will probably be PF, actually. P.5, as they say. But monsters can come from wherever. Actually, I'd better go check the PF SRD...

[Malimar]

You missed the humble wight. CR3, not incorporeal, reproduces quickly. Perfect for your purposes, I'd think.

I've got a town overrun by wights and quarantined in my campaign setting. Nobody's cleared it out or anything, but people have visited it a couple times. How it went depended on the level of the party -- low-level party barely made it out alive, high-level parties blazed through. Just as you'd expect.

[daremetoidareyo]

fell drain magic missile (http://www.dandwiki.com/wiki/SRD:Energy_Drain,_Negative_Levels,_and_Level_Loss) = Wight apocalypse

"A character with negative levels at least equal to her current level, or drained below 1st level, is instantly slain. Depending on the creature that killed her, she may rise the next night as a monster of that kind. If not, she rises as a wight."

[danzibr]

Huh. I can't find a humble wight. Even after googling it. It sounds perfect, but source?

Also, looking at PF SRD, I found this (http://www.d20pfsrd.com/bestiary/monster-listings/undead/zombie/zombie-apocalypse). Also seems good, but... a bit slow.

[Karl Aegis]

Some things to look into: Bleakborn (Libris Mortis), Spawn of Kyuss (Monster Manual 2) and Skull Lord (Monster Manual 5).

[Milo v3]

Huh. I can't find a humble wight. Even after googling it. It sounds perfect, but source?

Wights (http://www.d20srd.org/srd/monsters/wight.htm).WightText

Edit: How are Apocalypse Zombie's slow? 40 ft. speed, 20 ft. climb speed and Quick Strikes.

[Blackhawk748]

Lets not forget ghouls, the actually infect people with a disease and they become ghouls

Also Wights, Fell Drain + Damage spell = end of the known universe.