Insurgents struck Afghan security forces in Kabul and the north Sunday, killing 13 soldiers and policemen in attacks that show the Taliban's capability to strike far from their southern strongholds.

The attacks, both claimed by the Taliban, began at daybreak in the northern city of Kunduz, when four militants stormed an army recruitment center. At least two of the insurgents detonated suicide vests, and the remaining fighters battled security forces in a daylong firefight that left four Afghan army soldiers and four police dead, Kunduz deputy police chief Abdul Rahman Aqtash said.

The city, a major agricultural and marketing center that controls one of the main highways into neighboring Tajikistan, virtually shut down, with shops, the bazaar and administrative offices closing as the gunbattle raged, said Moeen Marastial, a parliament member from Kunduz.

The city was the last major urban center held by the Taliban in 2001, and militants began stepping up attacks there after NATO began using supply routes through former Soviet states bordering northern Afghanistan as alternatives to routes through Pakistan, where NATO convoys have come under frequent attack.

In Kabul, two insurgents strapped with explosives ambushed a bus carrying Afghan army officers to work during the morning rush hour on a main road into the city center, killing five and wounding nine, said Defense Ministry spokesman Gen. Mohammad Zahir Azimi.

It was the deadliest attack in the capital since May, when a suicide bombing against a NATO convoy killed 18 people, including six coalition troops — three American colonels and a Canadian colonel among them.