Several people have been shot inside a restaurant in the city of Goteborg and some of have died, Swedish police have said.

Police said in a statement that an automatic weapon is believed to have been used in the shooting late on Wednesday.

They had no details on any suspects but said an investigation was under way.

One witness told Swedish broadcaster SVT that two men entered the restaurant and started shooting with automatic weapons.

"I didn't have a chance to think about what happened. Then I saw that my friend was bleeding. I tried to stop the bleeding as good as I could with my hand," said the witness, who didn't give his name.

The shooting happened in an area of the city with a history of gang-related violence, police spokeswoman Ulla Brehm said. She said it was too early to speculate on the motive but said there were indications that the shooting was gang-related.

"There is absolutely nothing that indicates terrorism," Brehm said.

Goteborg is located in southwestern Sweden and is the country's second biggest city.