I was watching a bit on a live stream earlier and they said kids were taken away from a family by social services and it all kicked off from there. 5 kids were apparently left alone in a house and a young child allegedly ended up with a head injury. Thats backed up in the BBC article you posted
In a statement police said that on arrival officers found "an ongoing disturbance which involved some agency workers and some children".
A spokesperson said: "More people started to attend the location and a decision was made to remove the agency workers and the children to a safe place.
"A crowd started to gather and more officers were requested to attend the area, where some pockets of disorder were occurring.