Hamburg's Reeperbahn is famed for its bawdy nightlife – including brothels and strip bars – and also has a long connection to the harbour city's underworld.
And this appears to be the cause for a shooting which took place on Monday evening, which started when three members of the "Mongols" biker gang stepped out of a restaurant on the notorious street to have a cigarette.
At this point the trio were attacked by members of the rival "Hell's Angels" gang and fled in a taxi, eye witnesses reported.
But as the cab came to a halt at a red light, another car caught up and several men surrounded the car with their weapons drawn.
The bikers inside the taxi then pointed a gun at the taxi driver demanding that he drive away. Instead he pulled his key from the ignition and fled on foot, the Hamburger Morgenpost reports.
It was at this point that the shoot-out started, with seven shots being fired into the vehicle.
One of the men inside was seriously injured after being shot in the kidney and is now in hospital in critical condition.
Another member of the Mongols who had remained inside the restaurant broke a leg trying to escape and was also brought to hospital.
“Several shots were fired into the taxi. It looked like a sieve by the time it was over,” a spokesperson for Hamburg police said.
The taxi driver remained unharmed but "was in a state of shock,” the police officer added.
The subsequent police search involved 46 police cars. Twelve arrests were made, while police also seized weapons including a gun, a police report on the incident states.
A turf war of increasing violence has been raging over recent months between biker gangs over control of Hamburg's brothels.
In October unknown assailants planted a bomb under the car of the Mongols boss in an unsuccesful assassination attempt and in November he was attacked in the lift to his apartment.
According to Bild newspaper, other gangs are angry that the Mongols have become too powerful in the city's underworld.