3yo hitting in nursery school.At wits' end

[cosytidy]

My almost 4 yo started nursery school (2.5 hours a day) in Sept. when he started his behaviour turned terrible, he was hitting & throwing things in school & for the first time ever was hitting me at home. The we're telling me daily about hitting incidents & threatened SENCO.
I had a meeting with school, strategies discussed (no SENCO) & I told them the things I was doing to manage hitting at home. After a few days at home of me really focusing on his behaviour he stopped hitting me.
He occasionally has hit me since then (3-4 times in as many months)in a tantrum & he & his 2yo brother fight like mad. But the real issue is school.
His behaviour really improved in school for a bit & I had s positive parents' evening. But it's now returned to most days the teacher telling me of his hitting & on Friday, only a week into the term the teacher has asked me to come in for a meeting this week.
I'm at my wits end. I dread the school run, feel anxious & want to cry after a teacher has told me of an incident. Another mum at the school gives me dirty looks as my son hit her son previously. I loved the Christmas holidays with none of this going on.
He's a very bright, loving & sociable boy who I absolutely adore. Not much money at home but I make sure we go to parks, beaches, see family etc
Any suggestions?
For disclosure:
he eats well with limited junk,
is generally a good sleeper (tho can wake in the night a bit),
no issues at home,
no concerns about SEN/development,
I work part time.

Can he verbalise why he hits the other children? My DD1 has always been a really gentle girl but once in P1 she just flipped out and bit another little girl. Sometimes other children (even at nursery age) can be very passive aggressive and perhaps he's not used to it. Maybe talk more with him about why he feels the need to hit- is he cross or does he find it funny or is he frightened? I've never done mindfulness with my children but keep meaning to do it, if he's feeling cross then you could try that. Is it always the same child that he hits?

Thanks for the reply. On edge today, couldn't sleep last night thinking about this. And these things are always worse when sleep deprived!
Sometime he says he doesn't know, sometimes he'll say it's because of something a child has done. This may be because they had a toy he wanted or because they said something he didn't like so I try & give him other options & praise him when I see him walk away from a 'situation'. But that's difficult for me to have input on in nursery school.
He doesn't appear to do it with malice most of the time, but I know that's no comfort to the other child.
TBH I feel comfortable with how I deal with it at home & have had this affirmed by HV, teacher friends etc.
It's just school that's the issue

The we're telling me daily about hitting incidents & threatened SENCO.

That's sounds really tough. But the SENCO isn't a threat, it's an offer of help. If you and the nursery can't figure out what's going on at nursery then do get them to ask the SENCO to observe. Even if there aren't any special needs at all the SENCO will still be able to spend a while watching your DS to see what's leading up to the hitting and how the nursery deals with it.

It may just be that the more crowded busy atmosphere of nursery is triggering something for your DS that doesn't get triggered at home, and that he's burning a shorter fuse as a result.

Is he tired? If he stopped napping recently.
Or the preschool don t step in before he gets to that stage.
With dd1 she was pretty much fine at playgroup with me but nursery she was quite naughty mainly with staff. Then school much worse as the other kids were naughtier . Often as well possibly the other kid just wont stop or is snatching etc.
Imo school often stops the hitting but they then are verbally nasty to each other.
I thin k as much as possible it is the preschool responsibility to step in when he is getting cross. Plus some kids dont like being with so many others in a small room

Thanks for your replies.
I'd never thought of the general atmosphere, busyness triggering something for him. But it's understandable really. And I suppose how structured it is-in his other childcare while there are different activities going on he's free to play with what he likes. Whereas in nursery school he has to do/play where he's told.
I agree it would be better to intervene at triggering & other behaviour can be just as nasty as hitting.
I'd be happy for SENCO to be involved to suggest strategies but previously the 1 teacher told me it was happening then when I clarified with deputy head she said no.
On a postive note he had a good wk with stickers for good behaviour!