KABUL, Afghanistan » Teams of militants assaulted the Afghan army in the north of the country and in the capital killing at least 10 members of the security forces on Sunday, officials said.

On the outskirts of the Kabul, two insurgents strapped with explosives ambushed a bus carrying Afghan army officers to work during the morning rush hour, killing five, said Defense Ministry spokesman Gen. Mohammad Zahir Azimi.

One of the attackers managed to detonate his explosives, while soldiers shot the other dead, he said.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack.

A witness, Hamidullah Khan, said the gunmen ambushed the bus as it was heading down Jalalabad Road, a main route into the city center.

"The army vehicles were passing this road and then the Taliban or some sort of insurgents started shooting at them," Khan said.

In northern Kunduz province, four militants stormed an Afghan army recruitment center at daybreak, and at least one of them was able to detonate his explosives, said provincial deputy governor Hamdullah Danishi.

The assault killed three Afghan soldiers and two police officers, while three of the attackers also died, Danishi said, adding that the fourth was still battling government forces.

The blast shattered windows in nearby homes and gunshots could still be heard coming from the site hours later. Further details were not immediately available.

While most of the fighting in Afghanistan has been concentrated in the south, violence has increased elsewhere in the country this year, including in the north. The Obama administration released a mostly upbeat review of the war’s progress Thursday, although it suggest tough combat will continue for years and says gains made could be reversed.

The Afghan forces, which must take over responsibility for security in the country if international troops are to pull out, are frequently targeted in attacks.

In the south of the country, a NATO service member was also killed in a bomb attack, the international coalition said without providing further details.