The large explosion took place outside Kabul airport amid the evacuations of thousands of people from Western nations, the US Pentagon press secretary said on Thursday.
"Casualties are unclear at this time. We will provide additional details when we can," said spokesman John Kirby.
https://twitter.com/PentagonPresSec/status/1430888975917453313
The White House said President Joe Biden was briefed on the explosion.
Sky News correspondent Sally Lockwood said the blast occurred near the Baron hotel, where British troops and journalists have stayed.
The incident came after warnings earlier in the day that a "very lethal" terror attack could occur at the airport in a matter of hours.
A suicide bomber blew himself up, then heavy gunfire was heard, witnesses told Sputnik.
In the same vein, the UK, the US, in addition to other nations have been moving to end the evacuations of tens of thousands of citizens ahead of the 31 August deadline.