The incident took place in the restive Achin district, where the USA and Afghan forces have launched an intensive operation against IS rebels.
In separate news, a convoy carrying US and Afghan military personnel was hit by a roadside bomb and came under small arms fire today in Afghanistan's eastern Nangarhar Province.
The NATO color coding of the incident, "green or blue" indicates it may have been an apparent insider attack. The shooter was killed by return fire.
A similar incident occurred in March 2017, when an Afghan soldier was murdered because he attacked the United States soldiers in Helmand province; no causalities occurred, but 3 U.S. soldiers got wounded.
Baldridge, 22, of Youngsville, North Carolina, was one of three 101st Airborne Division soldiers killed Saturday in Afghanistan's Nangarhar Province, authorities said.
The other soldiers killed were special operators who died in firefights with ISIS militants.
Six American servicemembers have been killed in Afghanistan this year. The U.S. now has 8,400 American troops in the country, but U.S. officials say the military has proposed sending an additional 2,000 to 4,000 troops.
The Taliban said the attack was conducted by a member of its insurgency that infiltrated the Afghan forces.