Police suspect three men and a woman arrested during a DIA security incident Saturday may've been trying to stage some kind of protest.Humberto Aranguren, Katherine Bewersdorf, Larry Johnston, and John Hurley all face charges of disturbance and interference.A spokesman said police responded to a call about suspicious activity and found one man above the south security checkpoint using a video recorder as three other men and a woman went through the security line.Only the woman had identification and a boarding pass, said Denver police spokesman Sonny Jackson.7NEWS reporter Dayle Cedars reached Hurley by phone, but he declined to explain why he and the others tried to get through security without boarding passes or identification.A man believed to be Aranguren aggressively confronted Cedars and photojournalist Mike LeClaire in their car as they pulled up to his home. A man resembling Hurley videotaped the encounter.When asked if this was a "dry run" for terrorists, Jackson said, "Not necessarily. I won't speculate as to what that is. It could be that they want to see, 'How you're going to react to me without a ticket?' Or they just don't believe in the policies. We don't want to blow this out of proportion. It's important to keep it in perspective. You've got some individuals who were not armed. They had nothing that would lead us to believe that they had anything to do harm to anybody with. But they were basically trying to go through (security) without recognizing authorities and going through the proper procedures."Instead, sources told 7NEWS the woman gave screeners a letter, objecting to the full body scanners, demanding to be let through without any photographs being taken of her.Sources also told 7NEWS she requested payment in gold if her demands weren't met.Bewersdorf's Facebook page showed she studied aerospace engineering and worked on defense contracts with Boeing.While police stressed the four were not armed, sources explained that the incident was reported to FBI director Robert Mueller in Washington, D.C.Travelers said they thought the timing for the incident was poor, given Osama bin Laden's death less than a week ago and al-Qaida's threatened retaliation."My feeling, I'm kind of scared. I know Al Qaida's going to go after us," said Larry Christianson, a flyer from Oregon. "If people are going to mess with the system, especially at this point, I'd want to kind of call them aside and at least have a conversation.""I don't think it's good timing at all. I think that the airport and security should do whatever is necessary," said traveler Suzanne Rothman.