BERLIN, Feb. 19 (Xinhua) -- Fifteen people were left injured after the Cypriot-flagged 80-metre-long freighter "Raba" collided with 31-metre-long wind farm supply vessel "World Bora" sailing under Danish flag in the northeast Baltic sea of Germany on Tuesday.

Eleven technicians and four crew members of the "World Bora" were injured in the collision in the Baltic sea near Ruegen island. Ten people were seriously injured, while no one aboard the larger freighter "Raba" was injured, German water police announced.

The Danish ship was on the way to work at the offshore wind turbine park "Wikinger" in the Baltic Sea, where the deployment of technicians had been scheduled. The other larger freighter was heading from Copenhagen to the Polish city Szczecin.

The reason of the collision has not yet been established as "the affected ones" are still being treated in a hospital on the island of Ruegen, a spokesperson of Mecklenburg-Western Pomerania water police told Xinhua on Tuesday.

According to the police spokesperson, technical difficulties such as "failures of steering gears" as well as human failure and bad weather conditions such as windstorms are the most common reasons for collisions of freighters.

After the collision, the two ships were able to head to the ports of Ruegen on their own accord, where the crew of the German Maritime Search and Rescue Association (DGzRS) "Harro Koebke" performed emergency treatments before the injured seamen were transported to the hospital.