new baby & toddler nightime meltowns/tanttums

Hi. Iam in desperate need of help with 2 year old toddler. we have just had new baby 3 weeks ago and since this my 2 yr old has developed these type of night meltdowns/ tantrums. She goes bed ok but can wakes about 3-4 hrs later just all of sudden and go into meltdown. Dad goes in straightaway to try soith get back to sleep and can work it out but if gone into total meltdown stage then nothing we can do..shes seems so frightened and angry shes trying to tet out of bedroom n pushes us away n hits if we try touch her..she cries and is running about in a paniked state. she aware though as if we ask her something she says no no iam si upset i dont know what to di but i need to know how to handel this.