This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.conducted a drill at the Otay Mesa Port of Entry along the U.S.-Mexico border Saturday morning. The drill, called a “readiness exercise,” featured CBP officers blocking the border in riot gear and deploying fake tear gas. The exercise was similar to one that briefly delayed traffic at the San Ysidro Port of Entry on Thanksgiving Day. CBP officials planned to halt traffic at the border for the exercise for about 10 minutes, the agency said. The exercise came less than a week after a contentious showdown near the San Ysidro border crossing last Sunday, when Border Patrol agents fired tear gas canisters to turn back members of the migrant caravan who were trying to illegally cross into the United States. Since then, American authorities have arrested multiple caravan members for trying to cross the border. Meanwhile, some migrants moved to a new shelter in Tijuana over the weekend after heavy rain Thursday drenched an overcrowded, makeshift outdoor shelter near the border, making conditions much worse.