A massive fire roars through a neighborhood in San Bruno, Calif., after a PG&E gas pipeline ruptured, killing eight people, in 2010. Paul Sakuma/AP hide caption

Information cards are displayed during an Affordable Care Act enrollment event in San Antonio, Texas, in 2016. A federal judge struck down the health insurance law as unconstitutional Friday. Eric Gay/AP hide caption

Police officers stand near the place where Cherif Chekatt, the alleged gunman who had been a fugitive since allegedly killing three people at a popular Christmas market in Strasbourg, France, was shot dead by police on Thursday. Sebastien Bozon/AFP/Getty Images hide caption

Contractors work to reinforce a section of the U.S. border wall in San Diego where scores of Central American migrants have crossed illegally in recent weeks, shot through the fence from Tijuana, Mexico. Rebecca Blackwell/AP hide caption

French emergency services arrive at a Christmas market in Strasbourg, France, after a gunman killed at least three people and wounded nearly a dozen more. AP hide caption

Issac Rodriguez, from Sinaloa, Mexico, peers through the fence that divides Mexico and the U.S. in Tijuana, Mexico. Rodrigo Abd/AP hide caption

A portrait of Jose Antonio Elena Rodriguez, 16, a Mexican youth who was killed by a U.S. Border Patrol agent in Nogales, Mexico, in October 2012. Anita Snow/AP hide caption

Falcon 9 rocket first stage booster experiencing control problems and missing a landing zone at Cape Canaveral, Fla. John Raoux/AP hide caption

Juan David Ortiz, a U.S. Border Patrol supervisor, who was indicted Wednesday on charges of capital murder in the killings of four women in Texas. Webb County Sheriff's Office via AP hide caption

An F/A-18 Super Hornet fighter similar to one involved in an incident off the coast of Japan. Kin Cheung/AP hide caption

Secretary of Defense Jim Mattis testifying in October 2017 on Capitol Hill about immigrant military recruits. Manuel Balce Ceneta/AP hide caption

Former Dallas police officer Amber Guyger has been indicted on a murder charge in the killing of her black unarmed neighbor in his own apartment. AP hide caption

A street candy seller walks along the U.S.-Mexico border fence in Mexicali, Mexico, while U.S. Army soldiers fortify it with barbed wire. Defense Secretary Jim Mattis is likely to reduce the number of active-duty U.S. troops who are currently deployed at the Mexico border, from around 5,900 to around 4,000. Luis Boza/VIEW press/Corbis via Getty Images hide caption