ISIS took credit Saturday for a stabbing attack on a teenage German couple in Hamburg two weeks ago.

“A soldier of the Islamic State stabbed 2 individuals in Hamburg city on the 16th of this month. He carried out the operation in response to calls to target the citizens of coalition countries,” ISIS said in a statement released through Amaq News Agency.

On the night of October 16 in Hamburg, a 16-year old boy and his 15-year old girlfriend were attacked when sitting by the edge of the water below a bridge. The girlfriend, who was thrown in the river and survived, said that the boy was stabbed repeatedly when the assailant attacked from behind. The attacker remains on the loose.

ISIS has encouraged its followers to engage in a “campaign of knife attacks.”