CAIRO, Egypt — After three decades of iron-clad rule, Egyptian President Hosni Mubarak stepped down Friday and handed over power to the military.

Tens of thousands of emotional anti-government protesters erupted in deafening cheers on the streets of Cairo, reveling in their revolution. It was a moment they had been waiting for throughout 18 days of relentless demonstrations that demanded Mubarak’s departure.

“Egypt is free!” they chanted in the honeymoon of the moment. They waved Egyptian flags, honked horns and set off fireworks as they savored a moment that just days ago had seemed unimaginable.

Vice President Omar Suleiman announced the resignation on state television and said the Supreme Council of the Armed Forces will “run the affairs of the country.”

A source with close connections to Persian Gulf government leaders said that Mubarak had gone to the Red Sea resort town of Sharm el-Sheikh.

In a televised speech the night before, Mubarak had indicated he was delegating authority to Suleiman, but Friday, the crowds calling for his ouster swelled throughout Cairo and in other major cities.

Many of the anti-government protesters had been calling for Egypt’s powerful army, well-respected within the country, to take over as interim caretakers.

But what remains uncertain is what will come next in the most populous nation of the Arab world, and how Egypt’s revolution will reverberate throughout the region.

U.S. President Barack Obama was notified of Mubarak’s decision Friday morning, said Tommy Vietor, a spokesman for the National Security Council, and was closely watching the extraordinary developments unfold in Egypt, a key U.S. ally. He will make a statement Friday afternoon, the White House said.

Mubarak’s decision to step down is “obviously a welcome step,” said a U.S. official involved in the Egypt discussions. Now comes “an unpredictable next chapter,” the official added. It is “a sign the military chose society.”

Amre Moussa, the secretary-general of the Arab League, said Egyptians are “looking forward to a different (and) better future.”