Police in the northern German city of Kiel say they have detained four people after a group of men of foreign origin harassed three teenage girls at a shopping mall.

Police say Thursday's incident started with two Afghan men following the girls, aged 15 to 17, then photographing and filming them with their cellphones. The girls saw the men apparently sending the files to other people, and shortly afterward a group of between 20 and 30 men gathered and pestered them.

Authorities said Friday the girls weren't physically assaulted. They shook off the group, except the two Afghans. Mall security staff alerted police.

Police say four suspects were detained after they resisted and threatened officers. The two Afghans were taken into custody and the other two were released.