A U.S. soldier became the second American to be killed in Afghanistan this month after a firefight with Al Qaeda forces on Saturday, defense officials told Fox News.

U.S. Army Ranger Sgt. Leandro Jasso, 25, from Leavenworth, Wash., was wounded by small arms fire while conducting an operation to eliminate Al Qaeda militants in Nimruz Province, located in the southwest part of Afghanistan. Jasso was evacuated to Helmand province, where he was pronounced dead, officials said

"The loss of Sgt. Jasso is felt by his family and loved ones, by all who served with him and by all on this mission to protect our country and our allies," said Gen. Scott Miller, Resolute Support and United States Forces - Afghanistan Commanding General.

The Pentagon said that Jasso was assigned to 2nd Battalion, 75th Ranger Regiment, an elite unit within the U.S. military’s Joint Special Operations Command at Joint Base Lewis-McChord, Wash. He enlisted in the Army in August 2012 and was serving as a team leader on his third deployment to Afghanistan.

“Sgt. Jasso was a humble professional who placed the mission first, lived the Ranger Creed and will be deeply missed,” said Lt. Col. Rob McChrystal, Commander 2d Battalion, 75th Ranger Regiment.

The Pentagon said the incident remains under investigation. Jasso was the ninth American killed in action in the country this year, and the second this month after a former mayor from Utah who served in the state’s National Guard since 2013 was slain in an “insider attack" in Kabul on Nov. 3.

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Brent Taylor, a married father of seven children who was deployed to Afghanistan in January, was a former mayor of North Ogden, a city of about 17,000 people located about 46 miles north of Salt Lake City.

The killing of the American soldier on Saturday came as the Islamic State terror group in a statement posted on its Aamaq website which claimed responsibility for the suicide attack on Friday inside an Afghan Army base in eastern Khost province which killed at least 27 soldiers.

"The attack was carried out by a suicide bomber who detonated his explosive vest among them (army soldiers)," the ISIS statement said, without mentioning that the attack occurred inside a mosque at the base.

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The attack came just days after a suicide bomber killed 55 religious scholars gathered in the Afghan capital, Kabul, to celebrate the holiday marking the birth of Islam's Prophet Muhammad. The Taliban denied involvement in that bombing, which also wounded 94 people.

The U.S. and NATO formally concluded their combat mission in 2014, but still provide vital support to Afghan security forces, who have been struggling in recent years to combat a resurgent Taliban and an Islamic State affiliate. Some 15,000 U.S. soldiers are currently serving in Afghanistan.

International forces have also suffered from so-called insider attacks in recent months, in which Afghan soldiers or police have opened fire on them.

The Associated Press contributed to this report.