ITV News Global Security Editor Rohit Kachroo has the latest from the chaotic scenes around Kabul airport, as survivors are taken to nearby hospitals
President Biden has vowed to make Islamic State "pay" after two suicide attackers near Kabul airport in Afghanistan claimed the lives of 13 US military personnel.
At least 90 people were killed in the attacks on Thursday, the majority of them Afghans queueing at the airport desperate to be evacuated.
A further 143 Afghans were wounded, and 15 US troops injured.
The attackers struck at the Abbey Gate and near the Baron Hotel, where the UK has been processing Britons and Afghans eligible for evacuation.
President Joe Biden told a press briefing on Thursday that the attack was carried out by ISIS-K, an affiliate of the so-called Islamic State.
The US leader said his team had intelligence the group had been planning out "a complex set of attacks" on US forces and others - and said US commanders would strike back.
The president described the US troops who had lost their lives as "heroes" and said: "Our hearts ache for all those Afghan families who lost loved ones, including small children".
'We will not forgive, we will not forget, we will hunt you down and make you pay'
"For those who carried out this attack, as well as anyone who wishes America harm, we will not forgive, we will not forget, we will hunt you down and make you pay".
"These ISIS terrorists will not win," he added.
Pressed by journalists on the US decision to withdraw troops from Afghanistan, the president said he stood by his decision.
"I have never been of the view that we should be sacrificing American lives to try to establish a democratic government in Afghanistan," he said.
Earlier in the day US General Kenneth F. McKenzie said it was believed one of the attackers was undergoing checks by US officials in order to enter the airport - when the attacker detonated the device.
Speaking at a Pentagon briefing, the US military commander confirmed the attack was carried out by two suicide bombers assessed to be members of Islamic State.
'It was a hard day today,' General McKenzie told the media in his opening remarks
Gunmen went on to open fire on US forces and the crowds of people who have gathered at the airport for the past week - desperate to flee the country.
US military said it was in communication with the Taliban to prevent further attacks - while a Taliban spokesperson said it was "the presence of foreign forces" that had prompted such an attack.
The Ministry of Defence (MoD) said there had been no UK military or government casualties reported at an early stage.
Earlier on Thursday Boris Johnson warned of "many casualties" but stressed the evacuation process would continue.
Following a Cobra meeting on Thursday, the Prime Minister said the UK will continue with evacuations from Kabul, despite the blast.
Boris Johnson condemns the Kabul airport attackers - 'they're despicable'
"I want to stress that we’re going to continue with that operation – and we’re now coming towards the end of it, to the very end of it, in any event,” he added.
“But, clearly, what this attack shows is the importance of continuing that work in as fast and as efficient manner as possible.”
He described the attack as "barbaric" adding: "Members of the US military very sadly have lost their lives and [there are] many Afghan casualties as well."
The Foreign Secretary said US troops had "paid the ultimate sacrifice while helping others reach safety."
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In a statement following a call with US Secretary of State, Antony Blinken, Dominic Raab said: "I want to extend my condolences to the families of all those Afghans killed or injured. It is tragic that as they sought safety they have suffered at the hands of terrorists."
In a statement, Mr Raab continued: "Today’s attack is a stark reminder of the dangerous situation in which UK military and civilian personnel have been working so hard to evacuate people and we should be proud of their bravery and what they have achieved."
“The UK and US remain resolute in our mission to get as many people out as possible."
The UK has helped evacuate more than 11,000 people from Kabul, but many more have gathered around the airport - with desperate scenes of crowds surging towards the gates.
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ITV News spoke to a witness who was in the area when the blast hit but managed to avoid injury.
"People were killed- the ambulance was there. It was a horrible moment," he said.
"I am giving up on everything, I give up on evacuation.
"We will not go to the airport tomorrow because we saw a horrible scene today and I will not let my father, my family be a victim of that explosion, and be a victim of this killing and injuring."
The attack had been expected.
It came just hours after a UK government minister said there was an "imminent" terror attack threat from so-called Islamic State affiliated ISIS-K and warned British nationals to stay away.
Mr Johnson also said the UK had been prepared for the possibility of an attack.
"We always knew that this was a moment where there were going to be particular vulnerabilities to terrorism, to opportunistic terrorist attacks," he said.
"We condemn them, I think they’re despicable – but I’m afraid that they’re something that we’ve had to prepare for."
Thousands of Afghans have been gathered at the airport for days trying to flee the country following the Taliban's takeover of Afghanistan.
Conservative MP Alicia Kearns, a member of the foreign affairs and national security strategy committees, said there has been "so many hurt" in a bomb or gun attack at the Baron Hotel in Kabul.
She tweeted: "A bomb or attack with gun fire at northern gate of Baron’s hotel. Worried this will devastate evacuation – so many hurt. My heart is with all those injured and killed."
She added: "No I’m not just worried, I’m livid, and I’m heartbroken and I’m furious. The deals being done without UK input by ‘allies’. Taliban checkpoints stopping our people but not terrorists.
"There are people – damn good people – who for days have been trying to get out, now fleeing."
Labour leader Sir Keir Starmer said the reports from Kabul are “devastating”, adding: “Our thoughts are with all those killed and wounded, serving personnel supporting the evacuations and all those desperately trying to leave.”