Gunmen burst into a restaurant and opened fire in the southern Swedish city of Gothenburg late Wednesday, police said.
“Some died on the spot from gunshot wounds. The death toll can be expected to rise,” the police said in a statement.
Swedish newspaper Aftonbladet said “at least two” people were killed, without specifying a source.
A witness was quoted on national television as saying two men entered the restaurant and sprayed automatic gunfire.
The police statement confirmed automatic weapons were thought to have been used, and were treating the case as murder and attempted murder.
There were indications the attack was gang-related, police spokeswoman Ulla Brehm was quoted as saying by several local media.
The neighbourhood in Gothenburg, Sweden’s second-largest city, has a persistent gang crime problem, residents were quoted as saying by the Aftonbladet report.