CLEAN : Sirens sound in Israeli school as part of nationwide drill

The video discusses the importance of being prepared for missile attacks in schools. It highlights the need for safety measures and shelters, acknowledging the recurring nature of such threats. Despite having shelters, there are concerns about their effectiveness against multiple rockets.

What is the significance of the phrase 'missile attack on the school' in the context of the text?

What is the speaker's concern regarding the shelter's safety?