Plane and US soldiers in Kabul
Plane and US soldiers in KabulReuters

At least 70 people have been killed and 120 people wounded in a large explosion set off by a suicide bomber at Hamid Karzai International Airport in Kabul, Afghanistan on Thursday. All gates at the airport have been closed in light of the attack.

Pentagon Press Secretary John Kirby wrote on Twitter following the blast: "We can confirm an explosion outside Kabul airport. Casualties are unclear at this time. We will provide additional details when we can."

Kirby later added: We can confirm that the explosion at the Abbey Gate was the result of a complex attack that resulted in a number of US & 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."

At least three American soldiers were injured in the blast.

A short time later a second explosion was reported at the airport.

The attack follows warnings from the America, British, and Australian governments Thursday morning that a major terrorist attack at the airport was "imminent."

According to the warnings, the Islamic State (ISIS) was the source of the threat.

Thousands of westerners and Afghan citizens have flocked to the airport since the Taliban seized control of Kabul and the entire country on August 15, hoping to flown out of Afghanistan on one of the western aircraft participating in the evacuation.

Over 20 people have died in the chaos which has broken out at the airport, including several who clung onto planes as they took off and subsequently fell to their deaths and seven who were crushed to death in a stampede on Sunday.