Afghan officials say suicide bombers have killed at least four people and wounded 10 others in northern Afghanistan.

The Taliban claimed responsibility for Tuesday's attack in the city of Kunduz, the first major strike by insurgents in Afghanistan since the beginning of the Muslim holy month of Ramadan.

Officials say a suicide bomber detonated a car bomb just before dawn Tuesday outside a compound that houses two separate private security companies. Two other militants stormed the facility, triggering a gunbattle with police.

The fighting ended when the militants inside the building detonated their explosives.

Four private Afghan security guards were killed in the attack. An Afghan police officer was among those wounded.

One of the security companies housed in the compound worked for the German development and assistance firm GIZ. A company spokesman said Tuesday that GIZ was not a target in the attack. Officials say foreign nationals staying at the complex were able to escape.

Afghanistan's Interior Ministry condemned Tuesday's assault in Kunduz “in the strongest terms.”

Insurgents have carried out a number of recent attacks in what was once the relatively peaceful north.

In May, a suicide bomber killed the top police commander in northern Afghanistan, General Dawood Dawood, in Takhar province, which borders Kunduz province.

The following month, three police officers were killed when a suicide bomber attacked a memorial service for Dawood in Kunduz city.

Elsewhere, NATO said a bomb attack Tuesday killed one of its service members in eastern Afghanistan.