The U.S. Border Patrol said Wednesday that it found the wreckage of a small plane that disappeared two days earlier while carrying top U.S. and Mexico officials on a mission to survey flooding along the Rio Grande. There were no survivors.

The International Boundary and Water Commission said all four aboard the plane died, including the heads of its U.S. and Mexico sections.

The Border Patrol said it located the wreckage shortly after noon Wednesday in a rugged section of the Sierra Madre Mountains in Mexico, about 20 miles northwest of Presidio.

Kabul, Afghanistan

Gates apologizes for civilian deaths

Defense Secretary Robert Gates offered the people of Afghanistan his “personal regrets” Wednesday for U.S. airstrikes that have killed civilians and said he would try to improve the accuracy of air warfare, the imperfect fallback for U.S. commanders who say they don’t have enough ground forces for the deepening Afghanistan war.

“As I told them, I offer all Afghans my sincere condolences and personal regrets for the recent loss of innocent life as a result of coalition airstrikes,” Gates said after meeting with Afghan President Hamid Karzai. “While no military has ever done more to prevent civilian casualties, it is clear that we have to work even harder.”

Gates’ unusual apology followed a frank assessment from the top military commander in Afghanistan: There aren’t enough U.S. ground forces in Afghanistan, so the military is relying more heavily on air power. Air power runs a greater risk of civilian deaths in a country where insurgents do not wear uniforms and they intentionally mix with the general population.

Gates agreed to an Afghan proposal to establish a permanent U.S.-Afghan group to investigate all incidents involving civilian casualties.