Humanitarian medical NGO Emergency said its surgical center in Kabul had taken in more than 40 people who had been wounded in Wednesday’s explosion outside the Afghan Foreign Ministry complex.

"We have received more than 40 patients in the hospital, it is difficult to draw up a final number, we are continuing to respond," Emergency's Country Director in Afghanistan Stefano Sozza said, as quoted by the organization.

This comes after Kabul police spokesman Khalid Zadran said the blast had killed five civilians. Zadran also specified that a suicide bomber had tried to enter the ministry. He had been stopped by security but still managed to detonate his explosives.

Daesh claimed responsibility for the explosion, which it described as a suicide bomb attack, CCN reported.

Without providing evidence, Daesh’s Amaq news agency said the attack killed 20 people after one of its militants detonated an explosive belt in the middle of a crowd of workers near the main gate of the ministry. CNN stated that it could not independently verify the claim.

A former employee of the ministry meanwhile told CBS News that at least 13 people were killed, all of them employees of the foreign ministry.

Ahmadullah Muttaqi, a senior official at the prime minister’s office, said no foreigners had been at the ministry when the suicide bomber struck.

The ministry is located on a protected street in the diplomatic district of Kabul, where there are also several foreign embassies, former President Hamid Karzai's home, and other important government buildings.

In a tweet, the United Nations' mission in Afghanistan condemned the attack and said the "rising insecurity" in Afghanistan was "of grave concern."

Former Afghan President Hamid Karzai also condemned the attack, saying on Twitter that "this act of terrorism is a crime against humanity and against all human and Islamic values."

Both the US and Russia condemned the attack on foreign ministry employees.

United States Special Representative for Afghanistan Thomas West offered his condolences to the victims.

“My sincere condolences to the families of the victims of the terrorist attack in Kabul today, have seen reports of at least 20 dead and many more injured. This violence serves no purpose,” he tweeted.

Maria Zakharova, the official representative of the Ministry of Foreign Affairs of Russia said: “We express our sincere condolences on the occasion of the terrorist attack, as a result of which our Afghan colleagues - the employees of the Ministry of Foreign Affairs of Afghanistan were martyred.”