The police said that the cause for the accident was unknown. (Representational)

Nine people were killed when their plane crashed during a skydiving trip near Umea, a small university city in northern Sweden, authorities said on Sunday.

The small plane designed to carry parachutists crashed on an island on the Ume river shortly after take off, police spokesman Peder Jonsson said, adding the cause for the accident was unknown. He said those on board were on a skydiving trip.

The region's main University Hospital of Umea confirmed there were no survivors and relatives of the deceased had been notified.

Neither Jonsson nor the hospital immediately identified the victims' names or nationalities.