CBP is warning its agents to 'exercise extreme caution' after the Mexican military seized 10 IEDs at the border U.S. Customs and Border Protection is warning agents to be on the lookout for explosive devices. A federal law-enforcement source shared with FOX Business Network an internal officer safety alert dated December 13th that warns CBP agents to be vigilant after the Mexican military seized 10 improvised explosive devices (IEDs) at the border. The IEDs were found by Mexican authorities after Tucson border patrol observed gunshots at the U.S.-Mexico border and a Tucson supervisory border patrol agent arrested an armed person...