KABUL, Afghanistan — A roadside bomb exploded near a U.S. military vehicle on Saturday, killing four Marines in western Afghanistan in the deadliest attack against U.S. troops in the country this year, officials said.
The bomb in the western province of Farah targeted Marines helping to train Afghanistan's fledgling police force, said spokesman Lt. Col. David Johnson. Another Marine was wounded in the attack.
Marines from the 2nd Battalion, 7th Regiment based in Twentynine Palms, Calif., arrived in Afghanistan this year and were sent to southern and western Afghanistan to train police.
"The mission of the 2-7 Marines was to train and advise and mentor the Afghan National Police as part of the overall police reform strategy being employed here," Johnson said. "They're down there dedicating themselves to help create an institution that serves and protects the people of that region."
The bombing came one day after Defense Secretary Robert Gates told his counterparts in Europe that for the first time, the monthly total of American and allied combat deaths in Afghanistan exceeded the toll in Iraq during May.
The four deaths bring to at least 44 the number of U.S. troops killed in Afghanistan this year, according to an Associated Press count. No more than two U.S. personnel had been killed in any one attack in Afghanistan this year, according to the AP tally.