When Israeli commandos rappelled onto a flotilla of aid ships that were trying to break its Gaza embargo, they descended into a battle zone that left nine people dead and 30 injured, including several Israeli soldiers.
The violent confrontation also triggered a diplomatic firestorm and angry protests erupted in a dozen countries.
Israeli Prime Minister Benjamin Netanyahu, who was in Canada on his way to a White House meeting on Tuesday, canceled the meeting with President Obama. The two leaders later spoke briefly by phone and Obama said he "deeply regrets" the loss of life.
Netanyahu defended the use of force saying, "Our soldiers had to defend themselves, defend their lives, or they would have been killed."
The flotilla of six ships loaded with 600 protesters and tons of humanitarian supplies was organized by the Free Gaza Movement, an international coalition of pro-Palestinian activists, and a Turkish charity. Many of the passengers aboard the ships were Turkish.
There are conflicting reports about what happened during Israeli raid.
The Israeli navy confronted the convoy of ships in darkness, warning them to turn back. The ships refused. Communication between the ships and their families at home was cut off. Speedboats raced alongside and naval commandos dropped from helicopters.
An Al Jazeera correspondent, Jamad Al Shaid, on board the Mavi Mamara ship, reported that the Israelis fired at the vessel before boarding it.
"Tens of people have been injured, two killed, on board this ship which carries 600 activists, parliamentarians, women and children, and the elderly. All of them whom are civilians," the reporter said.
The Israelis, however, claimed their forces came under fire as they boarded the ships. Several Israeli soldiers were helicoptered away from the scene for medical care after suffering gunshots, stab wounds or bruises.
Avital Leibovitch, spokeswoman for the Israel Defense Force, said the Israeli naval commander offered several times to escort the ships to an Israeli port, but the flotilla captains refused.
She said the Israelis were met with a "preplanned violent attack," using knives, sticks and two pistols that were wrested from the Israelis. The Israelis boarded with their guns unloaded, Leibovitch said. People who attacked the Israeli commandos and took the pistols, also found the ammunition, loaded the pistols and used them against the Israelis, she claimed.
The Israelis allowed two of their commandos to speak, but identified them only by an initial.
First Sgt. Y said that his team was told they would be dealing with human rights activists, and he wasn't prepared for what met him when he rappelled to the deck of the Mavi Mamara armed with only a paintball gun used to subdue crowds.
"I came down and just saw war. I saw they were trying to kill us," he said.
As he rappelled down, First Sgt. Y found that people on the boat he fouled the lines to prevent the commandos from reaching the deck of the ship.
"We felt that they were really organized... With each guy who came down it was like a prepared attack," he said.
The first sergeant said when he landed on the ship he saw a comrade being attacked with pepper spray and steel clubs. "When they finished with him, they came for me," he said.
Others were thrown off the deck and landed in the water, the sergeant said. He saw another shot and spitting blood.
A commando identified only as "A" said that as they rappelled onto the deck, they were attacked, stripped of their equipment and weapons. At one point one of the passengers seized one of the soldiers' weapons and opened fire, he said.
Turkey's NTV showed activists beating one Israeli soldier with sticks as he descended from a helicopter onto the Mavi Mamara. Several passengers appeared to be bleeding and wounded in a report shown on Turkish television.
Video on a Turkish website showed pandemonium on board one of the ships, with activists in orange life jackets running around as some tried to help a colleague apparently unconscious on the deck. The site also showed video of an Israeli helicopter flying overhead and Israeli warships nearby.
Israeli Actions Invite Flurry of International Condemnation
At least three of the six ships were towed to the Israeli port of Ashdod. Some of the wounded had been taken to Israeli hospitals while others remained on a ship that had not yet arrived. Israeli officials said the people on board the ship would be processed at sea, and then deported.
A spokesman for the Israel foreign ministry said about 90 to 100 people were on the three ships already docked in Ashdod. About 25 of those people have agreed to be deported, but the others are refusing to identify themselves. Those refusing to cooperate hid their passports and some threw their passports into the sea, the spokesman said.
White House spokesman Bill Burton said the United States "deeply regrets the loss of life and injuries sustained." He said that administration officials are "currently working to understand the circumstances surrounding this tragedy."
The international reaction was more critical. The U.N. released a statement condemning the violence, and calling on Israel for "a full explanation."
"Such tragedies are entirely avoidable if Israel heeds the repeated calls of the international community to end its counterproductive and unacceptable blockade of Gaza," the statement read.
The violence also worsened Israel's relationship with Turkey, which had long been one of Israel's few friends in the Muslim world. Turkey announced that it was withdrawing its ambassador to Israel and demanded an emergency session of the U.N. Security Council.
The U.N. Security Council held an emergency session on the confrontation, hearing statements from the 15 council members as well as from Israel and the Palestinians. The council then went into closed consultations to consider possible action.
French President Nicolas Sarkozy released a statement condemning the "disproportionate use of force" and expressed his condolences to the families of the victims. France's Foreign Minister Bernard Kouchner said in a statement that "nothing can justify the use of such violence," and called for an investigation into the matter.
There were protests against Israel in Istanbul, London, Karachi, and Cairo. In Jerusalem today, government spokesmen were in "damage limitation mode."
Palestinian President Mahmoud Abbas described the incident as a massacre and has called for three days of mourning. Israeli police are on high alert in case of any retaliation.
The Associated Press contributed to this report