When is it permissible to intentionally interrupt the prayer, i.e., during its performance? Thank you.

Scholars agree on the prohibition of intentionally interrupting a fard (obligatory) prayer without a legitimate Shar'i (Islamic legal) justification, because it is a trifling with worship and contrary to its sanctity. They cite the Almighty’s saying: "And do not invalidate your deeds." As for voluntary (nafilah) prayers, the Hanafis and Malikis do not permit interrupting them without an excuse, while the Shafi'is and Hanbalis allow it, though they recommend not interrupting it. The first opinion is the more sound. Among the justifications for interrupting prayer (whether fard or nafilah) are: killing a snake, fear of losing property, assisting someone in distress, alerting an oblivious person or a sleeping person who is about to be harmed. It is also permissible to interrupt a nafilah prayer when the fard prayer is being established or for fear of missing the first rak'ah of it. There are other matters concerning which there is disagreement among the jurists.