KABUL: Afghan security forces ended an 11-hour standoff in central Kabul on Tuesday, killing the last gunman holding out after an attack that began when a car bomber blew himself up in a prosperous business and residential area.

Police sealed off the centre of the city as they battled three attackers who barricaded themselves inside an office of the aid group Care International.

After hours of standoff, interrupted occasionally by sporadic gunfire, Interior Ministry spokesman Sediq Sediqqi said Afghan Special Forces had killed all those involved in the attack in the Share Naw area of Kabul.

There was no immediate claim of responsibility for the attack, which took place just hours after Taliban suicide bombers killed at least 24 people near the Defence Ministry, including a number of senior security officials.

Initial casualty reports suggested one person had been killed and six injured while more than 31 people were evacuated.

The attacks highlighted the precarious security in the capital just a month before a conference in Brussels where international donors are expected to pledge continued financial support to Afghanistan.

After several hours of quiet overnight, gunfire and explosions could be heard as day broke.

Rafi Ullah, a security guard near the Care International office was walking in the area when the explosion occurred.

"Right after the explosion, a huge flame rose and everything was covered with smoke, and then Afghan security forces arrived and blocked the area," he said.

City traffic was blocked in several places and schools in the vicinity were closed.

Officers killed

Hours before the attack in Share Naw late on Monday, at least 24 people were killed and 91 wounded when twin blasts in quick succession tore through an afternoon crowd in a bustling area close to the Defence Ministry.

The Taliban quickly claimed responsibility for that attack, in which a suicide bomber caught security forces personnel and civilians who rushed to help victims of the first explosion.

An army general and two senior police commanders were among the dead, a Defence Ministry official said. Another official said the deputy head of President Ashraf Ghani's personal protection force had also been killed.

The double bombing came less than two weeks after gunmen attacked the American University in Kabul, killing 13 people. It was the deadliest attack in Kabul since at least 80 people were killed by a suicide bomber who targeted a demonstration on July 23. That assault was claimed by Islamic State.

The Taliban's ability to conduct coordinated attacks in Kabul has piled pressure on the Western-backed government, which has struggled to reassure a war-weary population that it can guarantee security.

Afghanistan's foreign partners, concerned about the ability of the security forces to withstand Taliban violence, are expected to pledge support over coming years at the Brussels conference, three months after NATO members reaffirmed their commitment at a meeting in Warsaw.

Outside Kabul, the insurgents have stepped up their military campaign, threatening towns including Lashkar Gah, capital of the strategic southern province of Helmand, as well as Kunduz, the northern city they briefly took last year.