According to unconfirmed reports in several Swedish newspapers, the girl did not appear to have been the intended target.
The Expressen tabloid reported that she was hit by a stray bullet aimed at two men with alleged links to a criminal network, with shots fired at them from a car.
“I cannot confirm any such reports, but want to underline that we are in great need of witnesses and observations. It's only when we have that that we can say what happened. Let us determine whether or not they are relevant observations,” local police chief Carolina Paasikivi told the TT newswire.
Police were called to the shooting at 3.27am on Sunday at a petrol station in the Norsborg area of Botkyrka, south of Stockholm. The girl was taken to hospital, but later died from her injuries.
No arrests had been made by Monday morning, but several people were being questioned. Police did not elaborate on what forensic teams had found, but said they would analyse CCTV footage.
“We will investigate and do everything in our power to bring the people behind this terrible act to justice,” national police chief Anders Thornberg told TT.
“We will collect witness statements, forensic evidence and all material that could help us move the investigation forward. But how successful we are also depends on those who know anything about the incident coming forward and helping us solve the crime.”
Sweden launched a so-called “special national incident” in November 2019 to look into violent gang crime incidents, but the number of shootings increased in the first four months of 2020 compared to last year.
Fifteen people were killed in 98 shootings between January and April, according to police statistics released earlier this year. In the same period of 2019, there were 81 shootings with 15 people killed.
However, the number of fatal shootings has remained relatively unchanged compared to previous years. Nine people were killed in 76 shootings during the same four months in 2018, and the year before that a total of 16 people were killed in 99 shootings.