Final answer:
After an incident where four students were killed, a faculty member pleaded with the remaining students to leave and peace was finally restored. However, there is no information about how the faculty members got unpetrified.
Step-by-step explanation:
In May 4, tensions reached a breaking point on campus, leading to an unfortunate incident where four students were killed and several others wounded by the National Guard. After this tragic event, the remaining students were urged by a faculty member to leave and peace was finally restored. There is no specific information on how the faculty members got unpetrified, as the reference material does not provide any details related to this question.