“Brutal and ruthless” Muslim, and “violent” Roma gypsy gangs are terrorising the streets of dozens of major European cities, as they vie for control of lucrative black market trade.

Running drug rings and pimping prostitutes, as well as owning legitimate street businesses can be worth tens of millions of euros a year – and more – to the immigrant criminal gangs of Europe. Having influence over territory is key to making this business model work, and as well as fighting each other the vast ethnic gangs are also fighting themselves, as influential families compete.

German magazine RP Online reports the scene at a Dusseldorf hospital this past weekend, which was turned into a fortress by state police to prevent what they feared were to be serious riots. A number of members of the same family had been admitted for treatment after a mass brawl and officers feared a siege as others attempted to finish the job.

Reports indicate that much of the infighting between the Roma gangs are over the ownership of women, while the Arabs are much more profit-motivated. Even in areas where gypsies have seized control of the prostitution rackets, they are still forced to pay protection money to the Muslims who rule the city, reports the Berliner Kurier.

Focus.de reports a theme often repeated in relation to these gangs, that they are ruthless, violent and exist entirely independently of national law. Running whole neighbourhoods of Germany’s largest cities, the Arab gangs operate their own parallel legal system, where the punishment for treason is death.

For Muslim shopkeepers who aren’t even part of the gangs, keeping a restaurant or hookah bar on the wrong street can mean enormous liabilities in protection money paid to one of the influential Arab gangs. Sustained non-payment of this money is punished with death. Likewise, anyone who “betrays his own people to the Germans, risks his life”, wrote hard-line judge Kristen Heisig before her mysterious death in 2010.

Her apparent suicide happened only days after she had submitted a manuscript for her latest book to her publishers, in which she warned without serious reform and a more hard-line attitude to gangs, Germany would “lose the struggle”. In the five years since, the situation has spiralled out of control as mass migration has provided re-enforcements for the gangs.

Berlin police estimate of the 30 criminal Muslim family clans in Berlin, each of which has up to 500 members, one tenth of all members are engaged in serious criminal activity at any given time. And they dominate the criminal landscape: a German senate report found that between 2011 and 2014, the majority of all gang crime suspects in the country were of “Arab origin”.

These conflicts are not without victims outside the Muslim and Gypsy communities. Only last month, a bloody shoot-out in Berlin last week between rival Muslim families caught a civilian in the crossfire. A 62-year-old artist was rushed to hospital in critical condition after she was struck in the thigh by a stray bullet as she rode by on her bicycle.

German police say the gangs are hard to crack because the national law enforcement system is not set out to deal with the problem. When individuals are arrests for gang crime their family structures aren’t recorded, so it becomes difficult for officers to build up pictures of who is related to whom, and how gangs operate.

Officers and prosecutors are crying out for new tools to fight the clans. A recent suggestion, taken from the Italian efforts to shut down the Mafia, to require suspected criminals to be able to prove large reserves of cash and hoardings of valuable assets are acquired through legitimate business has been mooted.