Really, all you had to do was point out that this was sourced from the Daily Mail.
The Daily Mail article links to an SVT article in Swedish which says pretty much the same thing. So much for "managing not to make it into the Swedish [media]".
Ehe... it's not at all worded in the same way.
The article focuses on two main areas.
1. The new refugees is putting a strain on police resources.
This doesn't mean that the refugees are criminals. It's also the police who's job it is to buss around refugees and put in them in the housing and camps they have. It's also the police who checks ID's on border crossings. This takes a lot of resources. This is mentioned as an explanation of why they're having trouble dealing with young Maroccans harrassing women and generally misbehaving.
2. The police are having problems with specifically young Maroccans being sent here alone without papers who then leave their housing and cause trouble. This isn't so much a critique against the young Maroccans. This is a critique against the responsible government agency who this one policeman says aren't taking their responsibility. It's also a critique against Maroccan government agencies who also aren't taking their responsibility. Just like Sweden takes care of juvenile delinquents, so does Marocco. Or should do. But they're clearly having trouble doing their job right. All according to this one anonymous Swedish policeman.
From the Daily Mail headline
"Swedish police warn Stockholm's main train station is now overrun by migrant teen gangs 'stealing and groping girls"
No, they're not. The police haven't. The SVT article has interviewed one policeman who wishes to stay anonymous. "Overrun", that's quite the visual. I'm guessing they asked the official police media representative who didn't want to comment. So I suggest not taking any of this seriously.
"Hundreds of Moroccan children living on the streets in Stockholm"
Not quite. These are kids who have been placed in housing and then sneak out at night after curfew. But then make it back. They're not running away. They're just doing what teenagers normally do. It's just that these don't have enough parental guidance.
"Accused of stealing and assaulting security guards at the main station"
This one anonymous policeman says that this has happened. Not that it's a runaway problem, or an epidemic. When they've been caught stealing the police take them back to their housing and nothing happens to the kids. This one policeman is whining about that they're state appointed guardians aren't reprimanding them for their behaviour. They're just letting them get away with it.
"Police say they grope girls and 'slap them in the face when they protest'"
Same here. This one policeman is saying it has happened. Not that it happens regularly or even a lot.
"One in five Moroccan migrant children run away from housing since 2012"
Did you never stay out later than what your parents told you to do when you were a kid? This is what they're talking about.
And finally... this is just one cops opinion. It says in the article. There's no official source for any of this. The official source denies this. So this could be just one racist cop talking shit.