Explosions were heard in the Iranian capital, Tehran, as Israel launched a preemptive strike. Israel is under a state of emergency, as Iran retaliated Friday night with missile attacks.

Aerial attacks between Israel and Iran continued overnight into Monday, marking a fourth day of strikes following Israel's Friday attack. That surprise strike hit the heart of Iran's nuclear program, killing several nuclear scientists as well as high-ranking military leaders, according to Israeli officials.

U.S. President Donald Trump will attend the G7 conference in Canada during a period of heightened tensions between the U.S. and its allies, as well as between Iran and Isarel.

As the attacks escalate, with fatalities and injuries reported on both sides, Israel issued the stark warning to Iran.