What actions necessitate interrupting prayer to address an emergency?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
If a person witnesses two small children fighting and fears one might throw the other into a well, he should intervene to save them and then return to his prayer. Similarly, if a man is pursuing someone who entered the mosque and then escaped after the Imam started praying, the pursuer should leave to seek him and then start his prayer anew. This applies if one sees a fire to extinguish or a drowning person to save; one should go to them and restart the prayer.
Supporting text
If a fire or flood reaches the worshipper while he is praying, he may flee from it and complete his prayer as the prayer of fear, based on the previously established principle.