It was 6.7, but it was shallow, which made it very destructive. I lived through the 6.8 here in Seattle five years ago. That one was deep, so it did much less damage.
Funny as the Whittier quake extracted more damage on my house than Northridge. Although Northridge was a wild ride.
It was much shallower than the Nisqually quake but not REALLY shallow; it was still fairly far underground on a blind thrust.
Also, most of the energy of Northridge was actually directed into fairly uninhabited mountains.
It could have been much, much worse...in timing as well.