Iran's Supreme Leader Ayatollah Ali Khamenei was killed, Iran's Fars News Agency reported on Sunday. 

The news agency, citing sources, also reported that four relatives of Khamenei, including his daughter, grandchild and son-in-law, were killed in the U.S.-Israeli strikes.

The Iranian government announced 40 days of public mourning. Meanwhile, the Islamic Revolutionary Guard Corps has vowed to take revenge against those responsible for the leader's death.

The United States and Israel launched what they described as "major combat operations" against Iran on Saturday. Israel had earlier stated that all senior Iranian government officials were potential targets. Israeli Prime Minister Benjamin Netanyahu said the goal of the joint military action was to "topple Iran's ruling regime."