I wasn't aware the minutemen were packing. I understood they were just spotters and called in the Federales when they spotted illegals. Is it true that they are armed?
I'm sure some are packing but Arizona has a concealed carry law...so, presumably those who are packing would, or could, be doing so whether they were in Tombstone or Tuscon.
Some are, some are not. The armed ones are in full compliance with applicable laws. Arizona has open carry sans permit and is a "shall issue" state for concealed carry permits. No permit is required for openly carried long arms. Additionally they recognize the permits of Alaska, Texas, Utah, Arkansas, Kentucky, Ohio, and Michigan.
You are correct, they are calling the US Border Patrol.
Is it true that they are armed?
Yes, some are, but only for self defense.