Six people, including children, were killed in a fire, which started in a building, located in Solothurn, northwest Switzerland, police said in a statement.
"For unknown reasons, a fire broke out in a building in Solothurn on Sunday night," the police said. "The rescue services arrived late ... Six people were killed, including children."
Police said the three-storey apartment building had more than 20 people who were evacuated by firefighters. An adjacent building has also cleared for prevention, police said.