At least 13 people, including children, were killed as two explosions took place near the Kabul airport in Afghanistan on Thursday evening amid a massive evacuation effort by Western countries, a Taliban official told Reuters. But, a spokesperson for the Taliban later told AFP that the toll could be as high as 20.

United States’ Department of Defense spokesperson John Kirby confirmed that the first blast took place near the Abbey Gate of the airport. About 30 minutes later, he confirmed another explosion near Baron Hotel, a short distance from Abbey Gate. He added that the attack resulted “in a number of US and civilian casualties”.

In a statement, Kirby said that “a number of US service members” were among those killed, without providing the exact figure. According to reports, there are about 5,200 American troops providing security at the Kabul airport.

Russia’s foreign ministry has also confirmed that there was a second explosion, according to AP. The news agency also said that at 13 people were killed. A local hospital told Reuters that it was treating more than 60 wounded people.

Afghan news channel TOLO News also reported that several people had been wounded in the blast and were taken to the Emergency Hospital in Kabul.

The channel’s owner Saad Mohseni tweeted pictures of the injured being moved in makeshift vehicles. Mohseni said he feared that there were “many casualties”.

Two unidentified US officials told Reuters that at least one of the explosions appeared to have occurred from suicide bombing.

Another unidentified source, who was in contact with a witness, told the news agency that two separate but simultaneous attacks took place. One of the blasts appeared to be a suicide attack by a bomber near buses queued up outside Abbey Gate, the source said. The blast was followed by firing from small arms, the source added, according to Reuters.

Another witness told TOLO News that the the blast occurred within a crowd of Afghans near Baron Hotel. They were trying to leave the country after the Taliban takeover.

However, the reports of suicide bombing have not been confirmed by any official yet. Kirby described the blasts as “result of a complex attack”.

Taliban spokesperson Zabihullah Mujahid condemned the attack and said that the insurgent group was paying attention to security arrangements, AP reported.

US President Joe Biden has been briefed on the explosions, an unidentified White House official told CNN.

The United Kingdom’s defence ministry tweeted that it was working to establish what had happened in Kabul and its impact on the evacuation of people from the country.

The explosion came hours after the United States, Australia and the United Kingdom issued three separate warnings about a threat of an attack by an affiliate of terrorist group Islamic State at the Kabul airport. Diplomatic and foreign offices of the three countries had urged people to evacuate the airport.

The warnings also came as allies of the North Atlantic Treaty Organization, commonly known as NATO, including Poland and Belgium, ended their evacuation efforts ahead of an August 31 deadline for the US troops to exit Afghanistan.

Canadian forces halted their evacuation process on Thursday, according to Reuters. Meanwhile, the US has said it will mainly pull out its own troops in the last two days.