Iranians on Saturday gathered in the streets of Tehran to demand Iranian Supreme Leader Ali Khamenei step down after the military shot down a civilian plane belonging to Ukraine International Airlines shortly after it took off from Tehran's airport.

The move killed all 176 people aboard the plane - at least 130 of them Iranian citizens.

Among other slogans, protesters shouted "death to liars," "death to the Islamic Republic," and "Khamenei is a killer." They also shouted "We want freedom," and "down with the lying regime."

Videos posted on Twitter showed hundreds of people demonstrating in front Tehran's Amir Kabir University, shouting, "Commander-in-chief [Khamenei] resign, resign."

Earlier on Saturday, Iranians held vigils around Tehran, mourning the victims of the crash.

Iran initially denied having anything to do with the crash, but US officials said early on that the plane had been shot down by the Iranian Revolutionary Guard Corps.

On Saturday, however, Iran finally admitted that it had made a mistake and shot the plane after it flew too close to a sensitive military site and failed to respond to signals.