They had $10,000 in cash on them. They gave false names and every question they answered was false. They were heading for San Antonio (which I understand was a major "wheel" in the drug distribution system out of Mexico - I DON'T expect any drug connection, though).
MAJOR news from the law enforcement was that the TIP that something was going down was an unauthorized phone call to Air Force One Tuesday morning just when Bush was heading back to D.C. The unauthorized caller (that in itself was a security violation) knew the code name for President Bush AND Air Force One! This is when they diverted to Barksdale A.F.B. and etc. The call occurred about the same time as the WTC events were unfolding.
Tightening up the chronology a bit, Pres. Bush made a brief statement in Florida around 9:30. In that statement, which I heard on C-SPAN, he said he was going back to Washington immediately, if I remember correctly. So any change in plans would have happened after that. That means the unauthorized call would have happened after Bush stepped up to the podium, very likely just around the time Air Force One was taking off from Florida. My guess is that the call was meant to divert Air Force One somehow, probably into some trap. It would be interesting to know precisely what the caller said.