The United States increased its pressure on Venezuela Friday, imposing sanctions on six high-ranking security officials as well as revoking the visas of dozens of other high officials.The Trump administration said the sanctions were a response to Venezuelan military officials, who last weekend blocked an opposition-backed effort to bring food into the country. At one border point, aid trucks caught fire and several people died. "We are sanctioning members of (President Nicolas) Maduro's security forces in response to the reprehensible violence, tragic deaths, and unconscionable torching of food and medicine destined for sick and starving Venezuelans," U.S. Treasury Secretary Steven Mnuchin said in a statement.Those being sanctioned include National Guard Commander Richard Lopez along with police and military officials based near the Colombian or Brazilian borders.The sanctions block any assets the officials have in the United States and bar Americans from doing business with them.The U.S. State Department also revoked the travel visas of 49 Venezuelans that it said were "individuals responsible for undermining Venezuela's democracy." The measures are part of an effort to pressure Maduro to step down. The United States sees his re-election last year as illegitimate and has recognized opposition leader Juan Guaido as interim president. Guaido, who also has the backing of about 50 other countries, has said that 300,000 people could die unless humanitarian aid reaches Venezuela. The U.S.-recognized president joined the aid convoy in Colombia, despite being ordered by Venezuela's Supreme Court not to leave the country. There, he met with U.S. Vice President Mike Pence and other regional leaders, and later traveled to Brazil and Paraguay. Guaido is next due to visit Argentina in his effort to gain support for his leadership and discuss strategies to hasten the departure of Maduro. He has said he will return home to Venezuela by Monday despite threats to arrest him.