India experienced a unique, sudden, unprecedented and extraordinarily large excess all-cause mortality event in April-July 2021, which is not adequately explained as a "second wave" or as being caused by a new variant of concern. After an overview of four recently published studies that have quantified the April-July 2021 excess all-cause mortality event, we give ten numbered arguments as to why we conclude that the extraordinary mortality event was caused by India's vaccine rollout in its early stages. Therefore, it appears that the early rollout of the vaccine in India in April-July 2021 was devastating, causing the deaths of approximately 3.7 million residents, on administering approximately 350 million doses of the vaccine.