Early Monday morning, Israel attacked a flotilla of aid ships bound for the Gaza Strip; at least 16 people were killed in the pre-dawn raid, according to organisers and media sources.
We'll be live-blogging the aftermath of this incident throughout the day; keep checking back for international reaction, news from our correspondents on the ground, photos and video. (All times are GMT, except where noted.)
Update, 10:57am: Israel's National Security Counter-Terrorism Bureau just issued a travel warning for Turkey, warning of the threat of "violent outbreaks" against Israeli citizens traveling there.
It advises Israelis to postpone any trips to Turkey; for Israelis currently in Turkey, it recommends that they "should remain in their places of residence, avoid city centers and sites in which demonstrations are being held, and monitor developments out of concern that the situation could worsen."
Update, 10:53am: Sheikh Hamad bin Khalifa al-Thani, the emir of Qatar, was one of the first Arab leaders to condemn the attack; he called it an "act of piracy" in a speech earlier this morning.
Before I conclude I must briefly refer to what happened this morning: The Israeli act of piracy against Arab and foreign activists, who tried to break a non-humanitarian, unjust siege imposed on our fellow citizens in the Gaza Strip, [imposed] for no reason but [that] they exercised their democratic right of choice. The crimes perpetrated this morning against the civilians supporting the Palestinians remind us of the unjust siege, the open bleeding wound in the [Gaza] Strip. All those who preach freedom, justice and democracy are required now to move, and to act to break this siege, so the blood of these free men does not go down the drain. This is a message addressed to the Arab states, who were brought to the moment of justice by those free men on board."
Update, 10:48am: The BBC is reporting that the Greek government canceled joint military exercises with Israel in protest over the attack.
Turkey's deputy prime minister announced a few moments ago that Turkey, too, is canceling joint drills with Israel.
Update, 10:43am: We're still trying to track down information about today's victims (various reports now put the death toll between 16 and 20).
We do know that the majority of the people on board the ships were Turkish. The passengers also include people from Algeria, Australia, Belgium, Canada, Germany, Greece, Ireland, Kuwait, Malaysia, Norway, Palestine, Serbia, Sweden, the United Kingdom, and the United States.
At least three of the German passengers were members of parliament.
Update, 10:38am: The Los Angeles Times is reporting a crowd of roughly 10,000 demonstrators in Istanbul today; they marched from the Israeli consulate to Taksim Square.
Turkish media, meanwhile, are reporting that the foreign ministry recalled Turkey's ambassador to Israel.
Update, 10:32am: The Egyptian foreign ministry issued a statement condemning the flotilla attack, according to Al Jazeera's Amr El-Kahky, who sends this note from Cairo summarizing the statement.
The spokesman sent his condolences for the families of the victims. He added that such actions remind the world that Gaza is still entirely under occupation calling for the immediate lifting of the blockade. He vowed that Egypt will continue to ease the suffering of Gazans by allowing more individual passage to and from the coastal strip and making sure aid heading for Gaza is delivered to the beseiged Palestinians.
The Egyptian government temporarily opened the Rafah border crossing with Gaza earlier this month, but it generally maintains tight controls over the movement of people and goods.
Jordan's government is expected to issue a formal statement in about a half-hour.
Update, 10:10am: We're hearing from Iraq that Moqtada al-Sadr has called for a large anti-Israel rally across from the Green Zone in Baghdad. The rally is scheduled to start around 5pm local time (2pm GMT).
Update, 10:04am: Raed Salah, a senior member of the Islamic Movement in Israel, was reportedly seriously wounded during the attack, and is being treated in a hospital in Israel.
Salah's deputy, Sheikh Kamel Khatib, told an Israeli radio station that Israel would be "directly responsible" if Salah was killed.
Update, 9:53am: More international condemnation continues to roll in:
Pakistan's foreign ministry issued a statement that "strongly condemns the use of brazen force by Israel."
The Jordanian foreign ministry has summoned the Israeli charge d'affaires, the ranking official at the Israeli embassy in Amman.
Saeb Erekat, the chief negotiator from the Palestinian Authority, called the Israeli attack "a war crime."
Update, 9:14am: The Stop the War Coalition and several other organisations are planning a rally this afternoon at 2pm local time (1pm GMT) outside the UK prime minister's residence.
Update, 8:59am: I just spoke with Greta Berlin, one of the flotilla's organisers, who said her organisation (the Free Gaza Movement) has had no contact with the passengers and crew on board the ships since they were attacked.
Berlin also strongly rejected the Israel's claim that the activists were the first ones to start shooting. She said there were no weapons on board the boats, and that any violence from the activists would have been in self-defense:
People certainly have the right to resist if they're being attacked. We taught our Free Gaza Movement people to be non-violent, and the Turks did the same, but if anyone resisted, it was in response to soldiers opening fire on them when they hit the deck.
Berlin also said organisers are still hoping to launch a second flotilla of boats, most of which remain at port in Cyprus.
We need to find out where the passengers are, where the crews are... and then we need to assess - we split up our flotilla, we have a second set of boats.
But Berlin said she didn't know when that second launch would happen; she expects it will be several days until everyone on board the first flotilla is accounted for.
Update, 8:43am: A statement from Saad Hariri, the Lebanese prime minister, who called the attack "dangerous and crazy":
The Israeli attack on the aid convoy is a dangerous and crazy step that will exacerbate tensions in the region.
Lebanon firmly denounces this attack and calls on the international community, notably major powers... to take action in order to end this continued violation of human rights and threat to international peace.
Update, 8:31am: Spain's foreign ministry has also summoned the Israeli ambassador for questioning. And Bernard Kouchner, the French foreign minister, described himself as "profoundly shocked" over the attack.
Update, 8:24am: An observation: We've heard a lot from the Israeli army, the Palestinian Authority, Hamas, the European Union, and a number of other governments.
The one party we haven't heard from in the last few hours is the organisers of the flotilla. Obviously it's impossible to reach those activists who were on board; and I haven't been able to reach their on-shore counterparts. The group's Web site hasn't been updated in the last few hours.
Update, 8:17am: This video, a report from Iran's state-run English-language Press TV network, shows a large crowd of protesters gathered outside the Israeli consulate in Istanbul this morning.