Three Taliban gunmen and one civilian have been killed in Kabul in a 12-hour police siege marking the end of a day of carnage in which 35 more people were killed and 103 wounded in twin suicide attacks outside the Afghan Ministry of Defence.

Militants forced entry into the offices of CARE International in Kabul's Shar-e Naw district late on Monday night (6 September), not far from where the earlier suicide bombings had targeted security officials.

The assault on the international NGO's offices was preceded by another suicide bombing close to the building. The three militants stormed inside in the ensuing chaos.

The siege was only broken at the end of a shoot-out in which the three militants were killed. At least one civilian was also killed and six others were wounded as a result of the attack, the Afghan interior ministry has said.

"Police special forces immediately reached the site of the attack and started rescuing people from the building .... 42 people who were trapped were evacuated by the security forces," the government said.

In one of the bloodiest attacks in the Afghan capital in recent weeks and since the start of the Afghan fighting season, the health ministry has confirmed 35 people were killed and 103 wounded in twin blasts targeting police and army officials.

One of the attackers was wearing a military uniform to blend in with security forces as they left work at the end of the day. The second attack was designed to cause maximum carnage as the suicide bomber targeted crowds which gathered at the scene.

"The second explosion was so strong, and many people, including security officials, were killed and wounded," Ashuqullah, a 34-year-old Afghan, told the Associated Press.

A district police chief and an army general were among those killed in the attack, three officials said independently.

The Afghan President Ashraf Ghani has condemned the attack in a statement, saying: "The enemies of Afghanistan have lost their ability to fight the security and defence forces of the country and thus attack highways, cities, mosques, schools and common people."