Fifteen people were injured - 10 of them seriously - after two ships collided near the German Baltic Sea island of Ruegen Tuesday, coastguard officials reported.

Officials said the Danish-flagged World Bora, a supply ship, collided with the Greek Cypriot-flagged Raba, a freighter, around 7:30 a.m. (0630 GMT) about 5 nautical miles off the coast. The cause of the accident was unclear.

All of the injured were on the World Bora - 11 workers and four crew members.

Both ships could reach harbor on the island under their own power. It is not known if any oil or other fuel spilled into the waters.

The cause of the crash is also unclear. The injured are not yet well enough to be interviewed by investigators.