Three German police officers deployed in Afghanistan were killed Wednesday by a roadside bomb near Kabul, local and German officials confirmed.

The officers were part of a group protecting the German ambassador and died while heading towards a training facility outside Kabul. A roadside bomb went off as two vehicles of the embassy were passing through the Bagrami district, one of the cars being destroyed despite its armour plating, security sources informed. 

A fourth officer was injured, Germany’s Interior Minister Wolfgang Schaeuble saying the servicemen involved in Wednesday’s incident are not part of the European Union police mission in Afghanistan.

Experts from the German Federal Criminal Police will be sent in the region to investigate the incident. Despite numerous attacks targeting German troops, Berlin said it won’t withdraw its forces from the region and will continue to cooperate with other EU members in Afghanistan.

Three German soldiers died in May after a suicide attacker detonated his explosive charge in a crowded market in the northern city of Kunduz. The incident provoked discontent among Germans, but the mission continues to have the support of most politicians.

Germany has deployed about 3,000 troopers in Afghanistan, most involved in reconstruction programs along with other servicemen from the International Security Assistance Force.