Late on Friday afternoon, military vehicles and troops swarmed the Turkish capital of Ankara and its most populous city, Istanbul. The country’s prime minister, Binali Yildirim, has gone on television to announce that this is a coup attempt by at least some portion of the military against the current government of President Recep Tayyip Erdogan.

A statement claiming to represent the Turkish armed forces claims to have seized control of the government. However, several hours later, a government spokesperson said the coup had been defeated. Emerging evidence suggests the government is telling the truth — among other things, Erdogan has landed in Istanbul, a thing he wouldn't do unless the security situation there is stable and in his favor.

A coup attempt in Turkey has precedent: Since the creation of the modern Turkish state, there have been four successful military coups. We don’t yet know what percentage of the military is involved in this coup, who the leaders are, or how likely they are to succeed.

This is a developing story, and the facts on the ground are likely to change. Here’s what we know and don’t know as of Friday night Eastern time.

What we know

Around 3:30 pm EST, reports began streaming in on social media of major military operations in Ankara and Istanbul.

In Ankara, tanks rolled through city streets, planes flew overhead, and military vehicles surrounded army HQ.

Istanbul’s two main bridges, the Bosphorus and the Fatih Sultan Mehmet, were blocked off by soldiers. Tanks rolled into Istanbul’s international airport:

Around 4 pm, Prime Minister Binali Yildirim went on TV to announce that it is a coup attempt. "A group in the military got engaged in a revolt," Yildirim said, according to New York Times columnist Mustafa Akyol.

Yildirim vowed not to let the coup succeed.

At around 4:30 pm, a statement sourced to the "Turkish Armed Forces" claimed that the military had seized control of the government.

The statement suggested the motivation was protecting Turkish democracy: "Turkish Armed Forces have completely taken over the administration of the country to reinstate constitutional order, human rights and freedom."

Erdogan, the country’s quasi-authoritarian leader and the real power in Turkey’s government, was on vacation and away from both Ankara and Istanbul when the coup began.

Around 5:30, Erdogan delivered an address to the nation via Skype. It blamed the coup on a "minority member of the military" and a "parallel structure." The latter phrase, according to Akyol, is a reference to the Gulenist movement — an influential religious and political movement that used to be aligned with Erdogan but has since turned against him.

Erdogan encouraged Turks to take to the streets in protest, specifically occupying airports and public squares.

In Ankara, demonstrators followed Erdogan's lead, taking to the streets to support his government.

The leader of Turkey's main opposition party has condemned the coup, suggesting limited support for the coup leaders in the political establishment.

An explosion rocket Turkey's parliament in Ankara. The casualty count is as-yet unknown, but it appears to be part of broader combat between pro- and anti-government factions.

There's also gunfire in Istanbul.

Around 7:45 pm, Turkey's national intelligence spokesperson announced that the coup had been "repelled." It is radically unclear whether that's true, but the fact that a Turkish spokesperson even feels comfortable saying that is significant.

Fethullah Gulen, leader of the Gulen movement, has denied links to the coup.

Late in the evening, Erdogan returned to Istanbul. This, per the New York Times, "is a strong sign the coup is failing."

What we don’t know