At least four civilians were killed and five others were wounded in an explosion in Kabul on July 13, police said, as the United Nations warned that Afghanistan was "on the brink" of a new humanitarian crisis as violence intensified amid a hasty withdrawal of U.S.-led forces from the war-torn country.
No group has claimed responsibility so far for the blast, which came amid an ongoing offensive by the Taliban militants who have captured around one-third of Afghanistan’s districts since the start of the foreign forces' pullout, raising fears that the government in Kabul could collapse.
The type of explosion and the target were not immediately clear, police said in a statement.
The blast occurred "in the center of Kabul" at rush hour, police spokesman Ferdaws Faramurz told journalists separately, adding that an investigation was under way.
SEE ALSO: Why The Taliban Is Sweeping Northern AfghanistanThe attack came as a senior Taliban leader on July 13 said that despite their military advances, the militants do not want to battle government forces inside Afghanistan's cities and urged them to surrender.
"It is better...to use any possible channel to get in touch with our invitation and guidance commission," said Amir Khan Muttaqi in a message tweeted by a Taliban spokesman, adding this would "prevent their cities from getting damaged."
Muttaqi is the head of a Taliban commission that oversees government troops who surrender to the militants.
His call came the same day as a video emerged that CNN said it had verified showing a team of Afghan commandos being shot dead by the Taliban last month after surrendering.
Meanwhile, the UN refugee agency warned on July 13 that more Afghans are likely to flee their homes due to escalating violence.
"Afghanistan is on the brink of another humanitarian crisis. This can be avoided. This should be avoided," Babar Baloch, spokesman of the UN High Commissioner for Refugees (UNHCR), told a Geneva news briefing.
"A failure to reach a peace agreement in Afghanistan and stem the current violence will lead to further displacement within the country, as well as to neighboring countries and beyond."
According to the UNHCR, some 270,000 Afghans had been newly displaced inside the country since January, bringing the total population forced from their homes to more than 3.5 million.
The number of civilian casualties has gone up 29 percent during the first quarter compared with last year, the UNHCR said, citing figures from the UN Assistance Mission in Afghanistan.
"We urge the international community to step up support to the government and people of Afghanistan and its neighbors at this critical moment," Baloch said.