Hehe. I found that source also, swamp.
I had about a half hour last night and found at least a dozen sources. All of them, seemingly, have a different version of the story. Here's a news special from the time on youtube:
http://www.youtube.com/watch?v=MAET3gFy5E8 I think it confirmed there were deputized citizens with deer rifles.
I found another where Martinez claimed he was almost shot by citizens on the ground. I found several that mentioned Crum(ex-military, head of security) as the only citizen involved. He was deputized by Martinez. I also found a couple that said Whitman was an ex-sniper in the military and that he was using a military sniper rifle(which is what I recalled).
I think, at the end of the day, there were probably several versions of the shooting. Almost 45 years later, it's probably impossible to know exactly what happened. FWIW, the news clip I linked shows plenty of people hiding but none are holding rifles. However, there were shots being fired from the ground pretty frequently. Could be cops, could be citizens.