"Three U.S. soldiers were killed in eastern Afghanistan today", a Pentagon statement issued Saturday said. In a statement from Washington, the Pentagon did not provide details about what led to the deaths of the USA soldiers.
The Taliban is claiming responsibility for the deaths, by using one of their members to infiltrate the Afghan Army.
Taliban spokesman Zabihullah Mujahid said the shooter was a member of the militant group and had killed four Americans and wounded several more. The details of this attack will be forthcoming.
In a statement, the Pentagon said the wounded soldier had been evacuated for treatment and the incident was under investigation.
Omar Zawak, spokesman for the governor of Helmand, said the deaths occurred when a USA aircraft fired on Afghan police, the statement said.
Six U.S. service members now have been killed in Afghanistan this year.
"This incident is under investigation", the statement said. "Our thoughts and prayers are with the families of American heroes".
The so-called "friendly fire" incident occurred overnight, during a raid in Afghanistan's restive Helmand province, the U.S. military command in Kabul said in a statement.
Excluding these three soldiers, four USA troops have already died in Afghanistan in 2017, with three of them being combat casualties. About 2,000 of them are involved in counterterrorism operations against al Qaeda and the ISIS affiliate in Afghanistan.
Dubbed the "Mother Of All Bombs", the GBU-43/B Massive Ordnance Air Blast was unleashed in combat for the first time April 12, hitting IS positions in a remote area of eastern Nangarhar province.
The number of insider attacks spiked in 2012 but have since become less common, a reduction attributed to new security procedures and better vetting of Afghan security forces.
Afghan President Ashraf Ghani surprised everyone at a peace conference Tuesday when he said that up to 11,000 foreign fighters have penetrated Afghanistan, a number far higher than previous estimates by the US military and his own government.
Achin has been the site of heavy fighting in recent months as U.S. Special Operations forces - including elite Army Rangers and Green Berets - have been working alongside Afghan commandos to rout the Islamic State from the area.
The Trump administration is in the middle of a review of the overall USA strategy in Afghanistan.