NATO says two U.S. service members have been killed in southern Afghanistan.

The two died after a bomb went off as they patrolled an area of Afghanistan that has seen some of the most intense fighting of the war.

The deaths Thursday come during the deadliest year for American troops during the eight-year Afghan war. They bring the total U.S. deaths in September to three.

Taliban attacks have grown this summer and there are now a record level of American forces in the country — more than 62,000.

U.S. military leaders are now contemplating asking for more troops to combat the increasing violence.