An Afghan army soldier turned his weapon on U.S. service members Saturday, killing three and injuring another in eastern Afghanistan.

The Afghan soldier was killed during the attack, said Attahullah Khogyani, spokesman for the provincial governor in Nangarhar province. Afghan officials initially said two servicemembers had been killed, but U.S. officials later said a third had died.

A statement from the U.S. military said the military was “aware of an incident in eastern Afghanistan.” White House spokesman Raj Shah told reporters traveling with the President Trump in New Jersey that Trump was “following the emerging situation in Afghanistan.”

The shooting occurred in Achin district, where U.S. special forces have been fighting alongside Afghan troops against Islamic State and Taliban militants, Khogyani said, according to Reuters.

Achin has been the scene of worsening violence in recent months as U.S. special forces and elite Afghan commandos intensify their efforts against ISIS loyalists in the region, a group known as ISIS Khorasan or ISIS-K, according to the Military Times.

The Taliban claimed responsibility in a statement by spokesperson Zabiullah Mujahid, who said a person loyal to the terror group infiltrated the Afghan army “just to attack foreign forces.”

Saturday's attack also comes as the Trump administration debates sending up to 5,000 additional American troops to Afghanistan to the help break what senior military leaders have declared a stalemate.

Vice President Mike Pence addressed the attack in his remarks at an event in Wisconsin on repealing Obamacare, according to ABC News.

"On my way here I was informed that U.S. servicemembers were killed and wounded in an attack in Afghanistan," Pence said. "The president and I have been briefed; the details of this attack will be forthcoming. But suffice it to say, when heroes fall, Americans grieve. And our thoughts and prayers are with the families of these American heroes."

Such insider attacks have happened before in Afghanistan. In March, another Afghan soldier was killed after he opened fire on foreign forces at a base in Helmand province, wounding three U.S. soldiers.

Contributing: Associated Press