In the past two weeks, police have arrested three young people believed to belong to a gang calling themselves the Black Scorpions, the Metro newspaper reports.

In one recent arrest, police apprehended a 17-year-old boy who had robbed a grocery store at gun point and then assaulted an older man who tried to intervene.

Police hope the arrest will help them gather more leads about the Black Scorpions, which they believe to be a youth feeder gang for the Black Cobras, a criminal gang with roots in the Danish capital of Copenhagen which has spread to Sweden in recent months.

“Arresting him is an important step in breaking the upward trend of serious robberies in the southern districts,” the police’s Johan Gustavsson told the newspaper.

Neighbourhoods in the south of Stockholm have been hit by a wave of violent thefts recently, with members of youth gangs high on the police’s list of suspects.

Police investigators continue to map out the various criminal networks, some of which they believe have members as young as 14-years-old, complicating the prospects for prosecution.

In Sweden, young people under the age of 15 cannot be criminally prosecuted, while offenders between 15 and 18 years old are only sentenced to prison for particularly heinous crimes.

Police suspect the robberies are part of the initiation process for gaining membership in the Black Cobra criminal gang.

“We’re gathering data on these young people through different types of surveillance. We’re using undercover surveillance, but we’re also finding youth suspected of belonging to different bands of thieves,” Gustavsson told Metro.

According to Danish press reports, the Black Cobras have been in existence for around ten years. The gang is believed to have been formed in Roskilde by Palestinian immigrants but has since also come to encompass criminals from a number of ethnic backgrounds, including Danish.