Sweden has gone from having one of the lowest rates of gun violence in Europe to having one of the highest, a report said on Wednesday, describing what one researcher called a "social contagion" of killings. Sweden, with a population of 10 million, saw 42 deadly shootings in 2019, the last year with verified statistics. Preliminary figures for 2020 also showed more than 40 people were shot dead. Of 22 European countries with comparable data that were analysed in the report from the Swedish National Council for Crime Prevention (BRA), only Croatia had more gun deaths per capita over the last four years. No other country had seen as swift an increase as Sweden. "Sweden has gone from almost the bottom of the ranking in Europe to very high up," Klara Hradilova Selin, researcher at BRA, told reporters at a news conference. Gun killings tend to follow one another, Selin said. "We do not know why. It is a kind of social contagion. If a shooting takes place, another usually takes place close in time and space," said Hradilova Selin. After a long period with a declining trend, deadly shootings began to increase in the mid-2000s and have continued to do so, the report found. That was in contrast to most other countries in Europe, where lethal violence, both in general and with firearms, has continued to decline. The report said eight out of 10 shootings took place in a "criminal environment", with gang conflicts mentioned as one of the potential reasons for the trend. The drugs trade and low confidence towards the police in some parts of society were also cited as potential factors.