Eep,as it had started rebuilting and may have changed a bit between the first and second failure it could make it much more trick. The best advice is to just turn it off and take it to a DR place now.

If you want to have a crack at it then get/borrow four more disks, DD all sectors from each source disk (mounted as read-only) to the working disks so that you can play without digging the hole deeper for yourself.

At that point your only real course of action is to use software like above that uses software to attpemt to reconstruct the RAID array in software bit by bit which, so long as the rebuild/fix attempts have not hosed it should be able to recover the data from only three of the disks.