Excerpts from Books and Wikipedia
"Theodosius, issued a decree ordering the destruction of all heathen temples. . . . When the Christian faction fought back, the pagans took hostages and barricaded themselves in the Sarapeum, the most imposing of the remaining temples. During the course of the siege, it was reported that some of the pagans plundered the temple while others tortured and sacrificed their helpless captives. Despite the ferocity of the incident, Theodosius spared the pagans but had the Serapeum destroyed, claiming that its pagan imagery had caused all the trouble. There is some debate about how much of the great library was contained in the Serapeum. If, as is widely believed, the Serapeum did house part of the library, its destruction was a tragedy that would have caused the loss of many ancient texts. However, at the time, this was probably not uppermost in the minds of most. There is no doubt that the violent events of 391 were seen by early Christians as further evidence of the triumph of Christianity over pagan mysticism." [1001 Days]