Here are the top 10 points in this big story:
Regionally-based ISIS-Khorosan, or IS-K, has claimed responsibility. According to news agency Reuters, the terror group said its suicide bombers had targeted "translators and collaborators with the American army". Intel from the United States and other sources appears to confirm this claim, Indian government sources have said.
US President Joe Biden has vowed vengeance, saying: "To those who carried out this attack, as well as anyone who wishes America harm, know this: We will not forgive, we will not forget, we will hunt you down and make you pay." General Frank McKenzie, head of US Central Command, told Reuters, US forces are on the alert for more attacks.
Biden also said the attacks would not force the US to alter plans to evacuate US citizens and refugees from Kabul by August 31 - the Taliban's deadline for withdrawal of forces. "We will rescue Americans who are there... we will get our Afghan allies out," Biden said.
The Taliban has also condemned the attack. There is no love lost between the ISIS and the Taliban, despite the fact both are hardline Sunni Islamist groups. They differ on the minutiae of religion and strategy, with each claiming to be the true flag-bearers of jihad.
The Taliban also hit out at foreign nations organising evacuations; a group official told Reuters they would not be held responsible for "chaotic evacuation plans". Western forces called on the Taliban to tighten security around the airport perimeter.
Around 160 Afghan Hindus and Sikhs may have narrowly escaped the blasts. Reports suggest they were at the airport a few hours before the attack looking for information on the next round of evacuations. They left the airport and the immediate vicinity and are now safe inside a gurudwara.
Video taken in the aftermath of the attack showed corpses floating in a canal by the airport fence; the video showed bodies being fished out and placed in a pile as family members and friends cried and beat themselves in sorrow. "I saw bodies and body parts flying (through) the air..." one witness told Reuters, "That little water flowing in the sewage canal had turned into blood."
Global leaders have condemned the "horrific" attack. British Prime Minister Boris Johnson called it "barbaric" and, like the US, said his country's evacuation efforts would continue. French President Emmanuel Macron condemned the attacks "with utmost firmness". The leaders of the Czech Republic, Egypt, Israel, Italy, Norway, Spain, Saudi Arabia and others also raised their voices.
Intel suggests the first blast took place at the Abbey gate of Kabul airport, which was being manned by American troops. Intel with India suggests the first bomber was wearing a suicide vest with IEDs attached. The second blast was near the Baron hotel close to the airport, where British troops and staff have set up base.
Over 100,000 have been evacuated since the Taliban swept to power on August 15. On Friday morning, some flights resumed with people lining up on the tarmac, but there were no crowds near the sites of the blasts, according to AFP reporters.
With input from AFP, Reuters