A few more comments in addition to put it into context:
The area just east of Frankfurt main station ("Bahnhofsviertel") is well known for its large number of drug dealers and users and a high likelihood of aggressive behavior against officials of any kind. Police currently tries to get the amount of criminal acts in the area down (it was better some years ago) by increasing their presence.
A large number of police officers doesn’t just appear out of nowhere to check a random group of people. Usually these are already suspected of some crime, e.g. having been observed by some other police men, possibly hidden in civilian clothing.
If there’s a group of, say, 5 people who are expected to not act cooperatively it just doesn’t make sense to turn up with less than a handful of officers if you want to keep them from fleeing.
Germany is (luckily) not a place where policemen make use of their weapons regularly. The total number of bullets fired by police at people is usually well below 100 per year in the whole of Germany. Especially in potential dangerous situations like these they simply try to outnumber the suspects to prevent any kind of escalation.
Aggression against officials (even paramedics) is unfortunately quite common in some places – not necessarily by the suspects themselves but by by-standers. Cases of two officers assisting someone and 6 more needed to keep aggressive, uninvolved people at distance are not unheard of.
As reported in the local news today, there was an actual raid in some bars and brothels in the area this weekend. They report to have checked and searched 300 people, found 9 with open arrest warrants and filed 60 reports about illegal substances and objects. This emphasizes how likely it is to find criminals in this area and explains the large amounts of police seen here – which is not representative for almost any other part of the city.
The reasons for the searches you have seen seems to be the fight against street-level drug trading (German news source). Occasionally there are also stronger-than-usual restrictions on the carrying of weapons, which would allow searches for pepper spray, knives, etc., but in the past those were temporary (German official declaration).
The police can question suspects of drug offenses, including searches. Then they either drop their suspicion or take further steps — the questioning is not, technically, a detention (vorläufige Festnahme), but those details might get lost in translation.
Some activists accuse the police in Frankfurt (federal police, not state police, in the train station) of racial profiling. I’m not qualified to judge how common that is.
In response to a comment made by Joe, about how to avoid being profiled: As someone who is not affected by racial profiling in Germany, I have no personal experiences to share, but I would suggest not hanging around at train stations without actually going somewhere, without luggage. People with suitcases who either come from a platform and leave the station or enter the station to go to a platform are less suspicious. Time of day also matters, but travelers don’t usually have control over that.
That won’t always help against cops who believe that the drug market is cornered by a specific ethnic group in their town …
Credit:stackoverflow.com‘