Pentagon press secretary John Kirby confirmed there was an explosion outside Kabul's Hamid Karzai International Airport.
Kirby tweeted, “We can confirm an explosion outside Kabul airport. Casualties are unclear at this time. We will provide additional details when we can.”
According to one US official, there are injuries among Afghans, but there is no information yet on any US casualties.
CNN's Barbara Starr noted that the situation continues to develop, and there are still few answers on what occurred.