This is bullying, but at this age schools can IME prefer to play it down as they are so young, but the impact on the DC being bullied is no less than when they are older & again from my experience with my own DD the softy softy approach & allowing it to be played down doesn't help long term -
amongst that group there will very likely be a ring leader who is orchestrating the whole class to exclude your DD - IME they really do start this young & younger & if not dealt with correctly & firmly enough now it will only escalate as the years go on.
Find out who the ring leader is, your DD will know, this will be the DC that the others all want to please & may even fear, they may not be the ones actually doing the hitting etc, but they will be the ones manipulating the others to do so.
My own DD had problems all through school with one girl ring leading, it started in reception, though my DD was always very popular with the other DCs but as the years went on they all became more & more afraid of the RL so that by year 3/4 it was full on bullying & exclusion of my DD - it affected her in much the same way you describe, though with pockets of things being okay for DD in between IYSWIM - took til year 5 before the school finally became more heavy handed with this girl, but by then she had such a hold over the others it was hard to break -
I allowed my DD Facebook & she kept in touch with her classmates via that on an evening/weekends - it was full of messages of support for her from some of the kids, basically owning up to " well you know what X is like, I'm not as brave as you" I hate what X does to you, they way X treats you etc etc etc - but in school they mostly kept their distance.
The only thing my DD did wrong was be strong enough to say no, & refuse to be manipulated by X - she realised after an incident in year 2 that X lied to you about others to get you to do her will & liked to control & hurt others, from there onwards DD wouldn't go along with it, from their own wards it got worse, affecting my DDs health badly
Thankfully X was taken out of school by her family, as they didn't like the fact that the school were no longer accepting it as high jinx & coming down harder on her.
In short don't be embarrassed, trust your instinct, gather the info, keep diaries, don't be afraid to call it what it is - bullying, but don't use that phrase directly with the school - refer to it as " bullying behaviours" (see links) - & ask what the school are doing to get to the bottom of it, stamp it out & support your DD in the mean time.
& Remind them of their legal " duty of care" to your DD, if your DD is suffering as much as you say, then they are failing in that & they need to step up to the mark & sort it out, because if not, it will only get worse.
Don't make the mistake That I made by accepting that they are so young that its not really what it seems to be - it is & your DD suffers as a result
These links will help you with understanding it & using the correct language when approaching the school will help you get a better response...
These are the government guidelines on it..., so will be what the school will work by, using these as a guide how to express your concerns, with out & out bullying accusations (even though you know that's exactly what it is) & what they should be doing to support your DD...
bullying Definition
understanding the roles & language to use
childline, good advice on supporting your DD
You can do a lot to help your DD, talk to her & listen well, try to find out if there's a root cause - what sort of things do they pick on her for, what do they say etc etc
In my DDs there seemed to be a lot of jealousy from the ringleader towards my DD, she envied her even for being ill & having accidents - DD according to her lied & did this for attention - X was a compulsive liar & did lie for attention - the old adage people hate most in others what they hate about themselves IME starts young -
she also didn't like DD because DD was clever, as was X, but DD was competition, she didn't like DD because she was liked for who she was, without lying or pretending, but most of all she didn't like DD, because DD wouldn't be told what to do by her, especially if it meant picking or hurting others
There could be all kinds of reasons, listen, watch & learn, that will prepare you best to support your DD & protect her self esteem & help her feel empowered, let her know the things they pick on her for are what makes her special & that they are either weak & afraid of the ring leader & Your DD is stronger than them, or that they are jealous of your DDs specialness
Then back it up with out of school clubs, making new friends outside of school that she sees weekly will again boost your DDs confidence.
All the advice above about circle etc time is good, also ask about buddy schemes - these are schemes where the school has a group of kids chosen to befriend the lonely ones at playtime & help them feel valued & help pair up other lonely DCs - my DD actually became a buddy & helped others, this helped her massively
Good luck