Our occupational therapist told us that it is not uncommon for a child with sensory integration (as my son has) to "hold it together" at school and then melt down afterwards at home. An aware child may be doing their very best at school and then just can't take it any longer and lose it in their safe place. Good luck
Visit school and see how it is organized. Could be anything - from lighting to wall colors. The calmer, the better:)
Possibly the teachers have a cooler ,calmer way of going about it, check out what triggers the tantrums could it be the way you are handling her needs.need some adjusting, we are closer maybe thats the thing.