UPDATE: A large explosion indeed occurred Thursday at one of the gates to the airport. You can check for updates here with the Associated Press, which still has reporters on the ground in Kabul.
This is the result of one of the many errors of the Biden withdrawal from Afghanistan: Abandoning Bagram Airbase, which is now in the hands of the Taliban.
There is only one runway at the Kabul airport, and the place is tough to defend. Our service members are in danger there, and the perimeter is not secured and clearly now being threatened by someone.
According to a bulletin by the U.S. embassy in Afghanistan.
Because of security threats outside the gates of Kabul airport, we are advising U.S. citizens to avoid traveling to the airport and to avoid airport gates at this time unless you receive individual instructions from a U.S. government representative to do so. U.S. citizens who are at the Abbey Gate, East Gate, or North Gate now should leave immediately.
The bolding of the sentence above is by the State Department, for emphasis.
Might be tough to get people into the airport if they can’t get to the gate.