As for the school's responsibility, Mr. Changping's article has already made an analysis, so I will not elaborate on it. Instead, I will try to talk about Fan Meizhong's personal responsibility.
Morally, we can say that Fan Meizhong abandoned his students and fled for his own life, which is cowardly and unscrupulous. But in terms of responsibility, it may only be limited to criticism. At most, one could hope for God's judgment or retribution in the afterlife, but this cannot involve his job or professional qualifications, etc. Because this should fall within the jurisdiction of current laws.
Legally, Fan Meizhong's actions constitute omission due to violation of the duty to rescue. However, since no harm was caused as a result, neither civil tort liability nor criminal charges can be established.