A third explosion hit the Afghan capital Kabul late Thursday in the wake of the twin bombings claimed by the Daesh terrorist group.
It remains unknown if there are any casualties so far.
At least 13 people were killed and 15 others injured earlier on the same day in twin bombings near the Kabul Hamid Karzai International Airport in Afghanistan.
The Pentagon confirmed two separate blasts occurred near the Kabul airport, with one explosion taking place at Abbey Gate and another targeting the nearby Baron Hotel.
"We can confirm that the explosion at the Abbey Gate was the result of a complex attack that resulted in a number of U.S. and civilian casualties. We can also confirm at least one other explosion at or near the Baron Hotel, a short distance from Abbey Gate. We will continue to update," said Pentagon spokesperson John Kirby.
Later, sources told Reuters that at least four U.S. military personnel were killed in the blasts.
Kirby separately said in a statement that "a number" of U.S. service members died in the attack but gave no specifics. Others were wounded and "a number of Afghans" also were victims, he said in a statement.