Israel launched strikes across Iran on Friday, saying they targeted the "heart" of Iran's nuclear programme.
With counter-attacks expected "in the immediate future", a state of emergency was declared in Israel.
Hossein Salami, chief of Iran's Islamic Revolutionary Guards - a powerful branch of the country's armed forces - was killed, Iranian state media reported, as well as nuclear scientists.
The US said it was not involved in the strikes, which also hit Iran's main nuclear enrichment facility.
Explosions were reported in Iran's capital Tehran around 03:30 local time (0100 BST).
