Should I report to social services?

So I wfh and every day without fail a young mum passes my flat constantly screaming, swearing and shouting at her daughter to keep up or for some other imagined infraction she's caused. I would estimate the girl is about reception age at school.

The poor girl is in tears almost every day and I've heard the mother use threats to 'make you stand in the corner all night facing the wall' 'lock you in your room tonight' and 'if you bite me I'll fucking bite you back' to name a few.

The mother clearly isn't coping very well but as a non parent I wonder if this behaviour crosses a threshold and should be reported? I don't want to be a busy body but equally I can't stop thinking about how horrible it must be for the poor girl. She also has a slightly older boy but he doesn't seem to incur her wrath at all

Update: I've called the school and left a VM outlining my concerns and given as accurate description of the mother as I could along with her quite distinctive pram.

I've also just got off the phone with local child protection services. They have said (as a few predicted) that without a name/address there isn't much they can do but that if the school contacts them they can move forward and if I have concerns the child is in immediate danger to contact the police.

As its the school holidays starting today I probably won't see them over the summer, wish I'd acted sooner so I could have got some evidence (I'll obviously still try to if I see them)

FURTHER UPDATE: School safeguarding person just rang me and said from my description they know who it is and will be taking it further. Thanks so much for all the advice and I just hope that little girl and her sibling(s) get the help and support they need