Cat suddenly attacking kids

Cats give warning signs before they attack usually.  Is his tail swinging or does he growl with his ears back or even hiss?  These are cues to not touch or mess with him right now.  A tense tail is not a good sign either.  He sees your daughters as button pushers and something to be reckoned with.  I am sure you try to stop their rough handling of him as soon as you can but he may be feeling smothered. 

He needs to have his own place that when he goes there, the girls know to leave him be.  Even if he's there all day.  He needs a place of escape and to feel safe.  Does he have that right now?  If not, find a spot for him and tell the girls never to bother him if he is there.  And watch to make sure they don't.  This will go a long way in him feeling secure and happy.  Like you, sometimes he just needs a break and he may not feel he gets that.  It is 4 against 1 after all. 

Another thing to do is to reintroduce the girls to him in a more positive way.  You need to show them how to respect his space and still interact with him a the same time.  You need to show him the girls aren't horrible monsters that he can't trusts.  Have the girls, 1 at a time preferrably with the others occupied doing other things so he doesn't feel overwhelmed, 1 at a time sit on the floor calmly with treats or toys and play with him.  Let him come to them.  You sit with them.  Mostly so you can monitor.  Start out slowly and calmly.  Show your girls 1 by one to let him give them permission to pet him.  Present their hands to him without grabbing or sudden movements and let him sniff and rub against it.  Then they can softly pet him. 

Once they all learn how to pet and play with him and how to respect his privacy time, he will be a much happier cat.  For good measure, you can try the Calming Collar or Feliway plug ins. 

^^ Great advice.

I would suggest that perhaps you find a room that the girls don't need to in, like your bedroom or the laundry room and set up his bed and food etc. Put a baby gate up. The cat can jump over and it will remind the girls that that room is "his" and when he goes there...they are not allowed to follow. I would also remind him that random hitting isn't acceptable. I firm "hey, hey" to show your displeasure. Teach your girls what to look for in his body language that warns he may swat. The last thing you need is an eye injury. Keep his nails trimmed too.

If you think he's got excess energy, perhaps you could purchase one of the fishing rod play toys and let the older girls tire him out.

Im wondering if he is not well. Cats in pain or stress dont have the same patience as usual. And tend to teach lessons whatever they are needed or not.

Several things you did wrote are sending hints into here. Both he apparently is in another mood. And his not attacking but teaching lessons slapping with soft paw.

I would suggest a visit to a good vet. Rather sooner than later.

Is he neutered?  Becoming fertile is NOT cause for such behaviour, but it may add.

There may be more advices, but seeing the vet is priority nr 1 at this moment.

Good luck!   *vibes*

ps. I agree with you being inside kitty is the best. Or at least - the very safest.    :)

The cat may be distressed of some sort, have you seen a vet lately for a routine check up? Also rough play will provoke such problem behaviors. The cat has become aggressive over time through rough play, and is now initiating rough contact on the kids, because the kids were allowed to be playfully rough with him, and now he's thinking its okay, to behave in such mannerism. Teach the children to make nice with kitty, and over time this will change your feline's behavior. Please refrain from rough play, as this encourages aggression.