According to the Washington Times article, the SS knew there was going to be trouble with the Chilean police:
In role reversal, president rescues Secret Service agent By James G. Lakely THE WASHINGTON TIMES
http://washingtontimes.com/national/20041120-113709-8651r.htm.
A second SS agent who was close behind was pushed into a wall in a near headlock, and remained outside.
Thanks for the link. I came late to the party and missed it all last night. Fox isn't being all that informative, so glad to read the WashTimes article.