....The U.S. also closed down one of two pedestrian bridges at the port of entry to prevent any stampede north
....Homeland Security Nielsen said border was 'closed' several hours after learning of plans immigrants would 'rush' crossing.
....members of the caravan 'purposely causing disruptions' along the border.
....5,000 caravan migrants have arrived in the Mexican border town, with up to 10,000 expected soon
....New caravan formed on Sunday in San Salvador and began heading north toward the US on foot and buses
