Yep, 12V is "safe" but when you have a few hundred amps availible and ya' short across it, things kind of get a bit hot let alone all the 'pirty sparks..
Definitely. So many times I've heard comments like "Oh, it's only a low voltage, it can't do any harm."
In the communications facility where I worked years ago we had the usual DC busbars running around above the racks for power. There were the usual 50V telephone equipment supplies, and we had a separate 28V distribution system for some of the satellite equipment. Some folk wouold scoff at the fuses and protection on that 28V system, but those busbars were fed from one heck of a big battery bank. The short-circuit current would have been well into the four-digit range, possibly even five.
At one point on the floor underneath the busbars was a patch where you could still see the burn marks from a slip made some years earlier. Apparently somebody accidentally dropped a wrench while working above on the cable trays and it bridged the bars as it fell. Needles to say, it was no longer usable for its intended purpose!