The Taliban claimed that attack.
On Saturday, Sgt. Leandro A.S. Jasso, a 25-year-old Army Ranger, was killed during an operation against al-Qaeda in southwestern Nimroz province, which borders Iran and Pakistan.
The three military members were killed on Tuesday in a roadside bombing near the city of Ghazni, the US military said, in what appeared to be the deadliest attack on USA forces in Afghanistan in the last 17 months.
"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", Gen. Scott Miller, commander of Resolute Support and U.S. Forces Afghanistan, said in a statement. Three other service members and one American contractor were wounded in the blast.
The 1TVNews reports no group immediately responsibility for the attack near the city of Ghazni, the provincial capital.
Earlier this month, Afghan President Ashraf Ghani said more than 28,000 Afghan police and soldiers had been killed since 2015.
Tuesday's blast also follows a visit to Ghazni last week by the top USA commander in the country, Gen. Scott Miller, to discuss the security situation.More news: Ireland deserved to win
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At least 11 United States service members have now died in Afghanistan this year, in combat or in so-called "insider attacks" by Afghan soldiers or police.
The coalition first identified Jasso on Sunday, but had not previously acknowledged the possibility of friendly fire. Jasso was evacuated to Helmand province, where he was pronounced dead, officials said. Brent Taylor of the Utah National Guard was killed in an "insider attack" by a rogue Afghan commando he was training in Kabul.
The United States now has some 14,000 troops in Afghanistan, serving in the NATO-led Resolute Support training and advisory mission as well as in separate counter-terrorism operations against militant groups like Daesh.
The total number of US military casualties during the 17-year Afghan war has been more than 2,400.
Several U.S. Special Forces troops were wounded and seven armored vehicles were disabled by enemy roadside bombs, mortars and rockets as they rushed to aid Afghan forces in repelling the Taliban assault, Time magazine reported in the wake of the battle.
"U.S. troops are fighting terrorism side-by-side with us".