They had a whole bunch of shit. Mostly HK91s like 199 said, but they also had a bunch of other stuff. Scoped bolt action rifles, shotguns with blank rounds for launching homemade rifle grenades, you name it. I seem to recall something about a getaway tunnel connecting two of their houses that were a block or so apart. I don't think they actually used anything but the HK91s, but it's been a while. They destroyed several cruisers, shot down a helicopter, killed one deputy, wounded several others and really made a mess of things. Their plan was to hide up in the hills until things quited down but the pursuit was too close and they had to abandon their supplies. They finally surrendered after a few cold, hungry nights.
Interesting example of (bad) luck: the getaway driver was killed after being hit by a single pellet of buckshot from a police shotgun. That one pellet hit him just behind the left ear and killed him instantly.