If you’re just joining us, here’s what you missed about the Ukraine International Airlines flight that crashed on Wednesday, killing all 176 people on board.

‘This disastrous mistake’: Iranian authorities said Saturday that the flight was mistakenly shot down, a conclusion Western intelligence officials had already reached. Iran’s President, Hassan Rouhani, said his country “deeply regrets this disastrous mistake” and vowed to investigate.

Foreign Minister Mohammad Javad Zarif said “human error at time of crisis caused by US adventurism led to disaster.”

Iran’s military also issued a statement on the crash, an unusual move for such a secretive organization. The statement said the plane was fired upon as it flew close to a sensitive military site “at an altitude and a condition of a flight that resembled (a) hostile target.”

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Calls for change: Those apologies and promises have not been enough to stop protests inside Iran.

Some demonstrators in Tehran called for Supreme Leader Ayatollah Ali Khamenei, the country’s top religious and political authority, to step down and for those responsible for downing the plane to be prosecuted. Khamenei has been Supreme Leader for three decades, and there is no limit to his term.

Protests spread to other cities, including Shiraz, Esfahan, Hamedan and Orumiyeh, Reuters reported.

Counter-demonstrations: Outside the United Kingdom’s Embassy in Tehran, Iranians gathered to protest after the UK Ambassador to Iran was arrested.

Ambassador Rob Macaire was held and then released Saturday, accused of instigating and directing radical and destructive demonstrations. Macaire said on Twitter that he wasn’t taking part in demonstrations, but was paying his respects to those who had been killed in the plane crash.