Israel and the US have launched a major attack on Iran after weeks of threats.
Israeli Prime Minister Benjamin Netanyahu said the objective was regime change, while US President Donald Trump called on Iranians to rise up and take control of their government.
Just after 6am (2.30am GMT), explosions were heard in multiple locations across Tehran, a Middle East Eye correspondent said.
Iranians are bracing themselves for even more devastating attacks than the 12-day war with Israel last year.
Missiles struck University Street as well as the Jomhouri and Seyyed Khandan areas, Iranian media reported.
