Complex sentence: After reaching the 26th floor by elevator, they encountered M. J. Gabour who, while clutching his wife's shoes,--screamed that his family had been shot and tried to wrestle the rifle from Day to shoot Whitman himself.
Split into simpler sentences: After reaching the 26th floor by elevator, they encountered M. J. Gabour. Gabour--clutching his wife's shoes--screamed that his family had been shot and tried to wrestle the rifle from Day to shoot Whitman himself.